diff --git a/src/libslic3r/BuildVolume.hpp b/src/libslic3r/BuildVolume.hpp
index 6b928d48b..be8d224c3 100644
--- a/src/libslic3r/BuildVolume.hpp
+++ b/src/libslic3r/BuildVolume.hpp
@@ -94,6 +94,12 @@ public:
     // Called on initial G-code preview on OpenGL vertex buffer interleaved normals and vertices.
     bool         all_paths_inside_vertices_and_normals_interleaved(const std::vector<float>& paths, const Eigen::AlignedBox<float, 3>& bbox, bool ignore_bottom = true) const;
 
+
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+    const std::pair<std::vector<Vec2d>, std::vector<Vec2d>>& top_bottom_convex_hull_decomposition_scene() const { return m_top_bottom_convex_hull_decomposition_scene; }
+    const std::pair<std::vector<Vec2d>, std::vector<Vec2d>>& top_bottom_convex_hull_decomposition_bed() const { return m_top_bottom_convex_hull_decomposition_bed; }
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+
 private:
     // Source definition of the print bed geometry (PrintConfig::bed_shape)
     std::vector<Vec2d>  m_bed_shape;
diff --git a/src/slic3r/GUI/3DScene.cpp b/src/slic3r/GUI/3DScene.cpp
index 23ca974dd..da09a236f 100644
--- a/src/slic3r/GUI/3DScene.cpp
+++ b/src/slic3r/GUI/3DScene.cpp
@@ -1,10 +1,12 @@
 #include <GL/glew.h>
 
+#if !ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
 #if ENABLE_SMOOTH_NORMALS
 #include <igl/per_face_normals.h>
 #include <igl/per_corner_normals.h>
 #include <igl/per_vertex_normals.h>
 #endif // ENABLE_SMOOTH_NORMALS
+#endif // !ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
 
 #include "3DScene.hpp"
 #include "GLShader.hpp"
@@ -69,6 +71,7 @@ void glAssertRecentCallImpl(const char* file_name, unsigned int line, const char
 
 namespace Slic3r {
 
+#if !ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
 #if ENABLE_SMOOTH_NORMALS
 static void smooth_normals_corner(TriangleMesh& mesh, std::vector<stl_normal>& normals)
 {
@@ -287,6 +290,7 @@ void GLIndexedVertexArray::render(
     
     glsafe(::glBindBuffer(GL_ARRAY_BUFFER, 0));
 }
+#endif // !ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
 
 const float GLVolume::SinkingContours::HalfWidth = 0.25f;
 
@@ -483,7 +487,9 @@ GLVolume::GLVolume(float r, float g, float b, float a)
     , force_neutral_color(false)
     , force_sinking_contours(false)
     , tverts_range(0, size_t(-1))
+#if !ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
     , qverts_range(0, size_t(-1))
+#endif // !ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
 {
     color = { r, g, b, a };
     set_render_color(color);
@@ -599,6 +605,36 @@ const BoundingBoxf3& GLVolume::transformed_non_sinking_bounding_box() const
     return *m_transformed_non_sinking_bounding_box;
 }
 
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+void GLVolume::set_range(double min_z, double max_z)
+{
+    this->tverts_range.first = 0;
+    this->tverts_range.second = this->model.indices_count();
+
+    if (!this->print_zs.empty()) {
+        // The Z layer range is specified.
+        // First test whether the Z span of this object is not out of (min_z, max_z) completely.
+        if (this->print_zs.front() > max_z || this->print_zs.back() < min_z)
+            this->tverts_range.second = 0;
+        else {
+            // Then find the lowest layer to be displayed.
+            size_t i = 0;
+            for (; i < this->print_zs.size() && this->print_zs[i] < min_z; ++i);
+            if (i == this->print_zs.size())
+                // This shall not happen.
+                this->tverts_range.second = 0;
+            else {
+                // Remember start of the layer.
+                this->tverts_range.first = this->offsets[i];
+                // Some layers are above $min_z. Which?
+                for (; i < this->print_zs.size() && this->print_zs[i] <= max_z; ++i);
+                if (i < this->print_zs.size())
+                    this->tverts_range.second = this->offsets[i];
+            }
+        }
+    }
+}
+#else
 void GLVolume::set_range(double min_z, double max_z)
 {
     this->qverts_range.first = 0;
@@ -611,7 +647,8 @@ void GLVolume::set_range(double min_z, double max_z)
         if (this->print_zs.front() > max_z || this->print_zs.back() < min_z) {
             this->qverts_range.second = 0;
             this->tverts_range.second = 0;
-        } else {
+        }
+        else {
             // Then find the lowest layer to be displayed.
             size_t i = 0;
             for (; i < this->print_zs.size() && this->print_zs[i] < min_z; ++ i);
@@ -619,7 +656,8 @@ void GLVolume::set_range(double min_z, double max_z)
                 // This shall not happen.
                 this->qverts_range.second = 0;
                 this->tverts_range.second = 0;
-            } else {
+            }
+            else {
                 // Remember start of the layer.
                 this->qverts_range.first = this->offsets[i * 2];
                 this->tverts_range.first = this->offsets[i * 2 + 1];
@@ -633,8 +671,9 @@ void GLVolume::set_range(double min_z, double max_z)
         }
     }
 }
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
 
-void GLVolume::render() const
+void GLVolume::render()
 {
     if (!is_active)
         return;
@@ -645,7 +684,14 @@ void GLVolume::render() const
     glsafe(::glPushMatrix());
     glsafe(::glMultMatrixd(world_matrix().data()));
 
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+    if (tverts_range == std::make_pair<size_t, size_t>(0, -1))
+        model.render();
+    else
+        model.render(this->tverts_range);
+#else
     this->indexed_vertex_array.render(this->tverts_range, this->qverts_range);
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
 
     glsafe(::glPopMatrix());
     if (this->is_left_handed())
@@ -680,25 +726,44 @@ void GLVolume::render_non_manifold_edges()
 }
 #endif // ENABLE_SHOW_NON_MANIFOLD_EDGES
 
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+std::vector<int> GLVolumeCollection::load_object(
+    const ModelObject*      model_object,
+    int                     obj_idx,
+    const std::vector<int>& instance_idxs)
+#else
 std::vector<int> GLVolumeCollection::load_object(
     const ModelObject       *model_object,
     int                      obj_idx,
     const std::vector<int>  &instance_idxs,
     bool 					 opengl_initialized)
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
 {
     std::vector<int> volumes_idx;
     for (int volume_idx = 0; volume_idx < int(model_object->volumes.size()); ++volume_idx)
         for (int instance_idx : instance_idxs)
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+            volumes_idx.emplace_back(this->GLVolumeCollection::load_object_volume(model_object, obj_idx, volume_idx, instance_idx));
+#else
             volumes_idx.emplace_back(this->GLVolumeCollection::load_object_volume(model_object, obj_idx, volume_idx, instance_idx, opengl_initialized));
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
     return volumes_idx;
 }
 
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+int GLVolumeCollection::load_object_volume(
+    const ModelObject* model_object,
+    int                  obj_idx,
+    int                  volume_idx,
+    int                  instance_idx)
+#else
 int GLVolumeCollection::load_object_volume(
     const ModelObject   *model_object,
     int                  obj_idx,
     int                  volume_idx,
     int                  instance_idx,
     bool 				 opengl_initialized)
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
 {
     const ModelVolume   *model_volume = model_object->volumes[volume_idx];
     const int            extruder_id  = model_volume->extruder_id();
@@ -706,6 +771,14 @@ int GLVolumeCollection::load_object_volume(
     const TriangleMesh  &mesh 		  = model_volume->mesh();
     this->volumes.emplace_back(new GLVolume());
     GLVolume& v = *this->volumes.back();
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+#if ENABLE_SMOOTH_NORMALS
+    v.model.init_from(mesh, true);
+#else
+    v.model.init_from(mesh);
+#endif // ENABLE_SMOOTH_NORMALS
+    v.model.set_color(color_from_model_volume(*model_volume));
+#else
     v.set_color(color_from_model_volume(*model_volume));
 #if ENABLE_SMOOTH_NORMALS
     v.indexed_vertex_array.load_mesh(mesh, true);
@@ -713,9 +786,9 @@ int GLVolumeCollection::load_object_volume(
     v.indexed_vertex_array.load_mesh(mesh);
 #endif // ENABLE_SMOOTH_NORMALS
     v.indexed_vertex_array.finalize_geometry(opengl_initialized);
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
     v.composite_id = GLVolume::CompositeID(obj_idx, volume_idx, instance_idx);
-    if (model_volume->is_model_part())
-    {
+    if (model_volume->is_model_part()) {
         // GLVolume will reference a convex hull from model_volume!
         v.set_convex_hull(model_volume->get_convex_hull_shared_ptr());
         if (extruder_id != -1)
@@ -732,6 +805,16 @@ int GLVolumeCollection::load_object_volume(
 // Load SLA auxiliary GLVolumes (for support trees or pad).
 // This function produces volumes for multiple instances in a single shot,
 // as some object specific mesh conversions may be expensive.
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+void GLVolumeCollection::load_object_auxiliary(
+    const SLAPrintObject* print_object,
+    int                             obj_idx,
+    // pairs of <instance_idx, print_instance_idx>
+    const std::vector<std::pair<size_t, size_t>>& instances,
+    SLAPrintObjectStep              milestone,
+    // Timestamp of the last change of the milestone
+    size_t                          timestamp)
+#else
 void GLVolumeCollection::load_object_auxiliary(
     const SLAPrintObject 		   *print_object,
     int                             obj_idx,
@@ -741,6 +824,7 @@ void GLVolumeCollection::load_object_auxiliary(
     // Timestamp of the last change of the milestone
     size_t                          timestamp,
     bool 				 			opengl_initialized)
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
 {
     assert(print_object->is_step_done(milestone));
     Transform3d  mesh_trafo_inv = print_object->trafo().inverse();
@@ -753,12 +837,21 @@ void GLVolumeCollection::load_object_auxiliary(
         const ModelInstance& model_instance = *print_object->model_object()->instances[instance_idx.first];
         this->volumes.emplace_back(new GLVolume((milestone == slaposPad) ? GLVolume::SLA_PAD_COLOR : GLVolume::SLA_SUPPORT_COLOR));
         GLVolume& v = *this->volumes.back();
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+#if ENABLE_SMOOTH_NORMALS
+        v.model.init_from(mesh, true);
+#else
+        v.model.init_from(mesh);
+#endif // ENABLE_SMOOTH_NORMALS
+        v.model.set_color((milestone == slaposPad) ? GLVolume::SLA_PAD_COLOR : GLVolume::SLA_SUPPORT_COLOR);
+#else
 #if ENABLE_SMOOTH_NORMALS
         v.indexed_vertex_array.load_mesh(mesh, true);
 #else
         v.indexed_vertex_array.load_mesh(mesh);
 #endif // ENABLE_SMOOTH_NORMALS
         v.indexed_vertex_array.finalize_geometry(opengl_initialized);
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
         v.composite_id = GLVolume::CompositeID(obj_idx, -int(milestone), (int)instance_idx.first);
         v.geometry_id = std::pair<size_t, size_t>(timestamp, model_instance.id().id);
         // Create a copy of the convex hull mesh for each instance. Use a move operator on the last instance.
@@ -774,6 +867,17 @@ void GLVolumeCollection::load_object_auxiliary(
     }
 }
 
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+#if ENABLE_WIPETOWER_OBJECTID_1000_REMOVAL
+int GLVolumeCollection::load_wipe_tower_preview(
+    float pos_x, float pos_y, float width, float depth, float height,
+    float rotation_angle, bool size_unknown, float brim_width)
+#else
+int GLVolumeCollection::load_wipe_tower_preview(
+    int obj_idx, float pos_x, float pos_y, float width, float depth, float height,
+    float rotation_angle, bool size_unknown, float brim_width)
+#endif // ENABLE_WIPETOWER_OBJECTID_1000_REMOVAL
+#else
 #if ENABLE_WIPETOWER_OBJECTID_1000_REMOVAL
 int GLVolumeCollection::load_wipe_tower_preview(
     float pos_x, float pos_y, float width, float depth, float height,
@@ -783,6 +887,7 @@ int GLVolumeCollection::load_wipe_tower_preview(
     int obj_idx, float pos_x, float pos_y, float width, float depth, float height,
     float rotation_angle, bool size_unknown, float brim_width, bool opengl_initialized)
 #endif // ENABLE_WIPETOWER_OBJECTID_1000_REMOVAL
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
 {
     if (depth < 0.01f)
         return int(this->volumes.size() - 1);
@@ -839,9 +944,16 @@ int GLVolumeCollection::load_wipe_tower_preview(
 
     volumes.emplace_back(new GLVolume(color));
     GLVolume& v = *volumes.back();
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+    v.model.init_from(mesh);
+    v.model.set_color(color);
+#else
     v.indexed_vertex_array.load_mesh(mesh);
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
     v.set_convex_hull(mesh.convex_hull_3d());
+#if !ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
     v.indexed_vertex_array.finalize_geometry(opengl_initialized);
+#endif // !ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
     v.set_volume_offset(Vec3d(pos_x, pos_y, 0.0));
     v.set_volume_rotation(Vec3d(0., 0., (M_PI / 180.) * rotation_angle));
 #if ENABLE_WIPETOWER_OBJECTID_1000_REMOVAL
@@ -856,6 +968,22 @@ int GLVolumeCollection::load_wipe_tower_preview(
     return int(volumes.size() - 1);
 }
 
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+GLVolume* GLVolumeCollection::new_toolpath_volume(const ColorRGBA& rgba)
+{
+    GLVolume* out = new_nontoolpath_volume(rgba);
+    out->is_extrusion_path = true;
+    return out;
+}
+
+GLVolume* GLVolumeCollection::new_nontoolpath_volume(const ColorRGBA& rgba)
+{
+    GLVolume* out = new GLVolume(rgba);
+    out->is_extrusion_path = false;
+    this->volumes.emplace_back(out);
+    return out;
+}
+#else
 GLVolume* GLVolumeCollection::new_toolpath_volume(const ColorRGBA& rgba, size_t reserve_vbo_floats)
 {
 	GLVolume *out = new_nontoolpath_volume(rgba, reserve_vbo_floats);
@@ -872,6 +1000,7 @@ GLVolume* GLVolumeCollection::new_nontoolpath_volume(const ColorRGBA& rgba, size
 	this->volumes.emplace_back(out);
 	return out;
 }
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
 
 GLVolumeWithIdAndZList volumes_to_render(const GLVolumePtrs& volumes, GLVolumeCollection::ERenderType type, const Transform3d& view_matrix, std::function<bool(const GLVolume&)> filter_func)
 {
@@ -960,7 +1089,10 @@ void GLVolumeCollection::render(GLVolumeCollection::ERenderType type, bool disab
         glsafe(::glEnableClientState(GL_VERTEX_ARRAY));
         glsafe(::glEnableClientState(GL_NORMAL_ARRAY));
 
-        shader->set_uniform("uniform_color", volume.first->render_color);
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+        if (!volume.first->model.is_initialized())
+#endif // !ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+            shader->set_uniform("uniform_color", volume.first->render_color);
         shader->set_uniform("z_range", m_z_range, 2);
         shader->set_uniform("clipping_plane", m_clipping_plane, 4);
         shader->set_uniform("print_volume.type", static_cast<int>(m_print_volume.type));
@@ -980,6 +1112,10 @@ void GLVolumeCollection::render(GLVolumeCollection::ERenderType type, bool disab
 #endif // ENABLE_ENVIRONMENT_MAP
         glcheck();
 
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+        if (volume.first->model.is_initialized())
+            volume.first->model.set_color(volume.first->render_color);
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
         volume.first->render();
 
 #if ENABLE_ENVIRONMENT_MAP
@@ -1215,6 +1351,466 @@ std::string GLVolumeCollection::log_memory_info() const
 	return " (GLVolumeCollection RAM: " + format_memsize_MB(this->cpu_memory_used()) + " GPU: " + format_memsize_MB(this->gpu_memory_used()) + " Both: " + format_memsize_MB(this->gpu_memory_used()) + ")";
 }
 
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+static void thick_lines_to_geometry(
+    const Lines&               lines,
+    const std::vector<double>& widths,
+    const std::vector<double>& heights,
+    bool                       closed,
+    double                     top_z,
+    GUI::GLModel::Geometry&    geometry)
+{
+    assert(!lines.empty());
+    if (lines.empty())
+        return;
+
+    enum Direction : unsigned char
+    {
+        Left,
+        Right,
+        Top,
+        Bottom
+    };
+
+    // right, left, top, bottom
+    std::array<int, 4> idx_prev    = { -1, -1, -1, -1 };
+    std::array<int, 4> idx_initial = { -1, -1, -1, -1 };
+
+    double bottom_z_prev = 0.0;
+    Vec2d  b1_prev(Vec2d::Zero());
+    Vec2d  v_prev(Vec2d::Zero());
+    double len_prev = 0.0;
+    double width_initial = 0.0;
+    double bottom_z_initial = 0.0;
+
+    // loop once more in case of closed loops
+    const size_t lines_end = closed ? (lines.size() + 1) : lines.size();
+    for (size_t ii = 0; ii < lines_end; ++ii) {
+        const size_t i = (ii == lines.size()) ? 0 : ii;
+        const Line& line = lines[i];
+        const double bottom_z = top_z - heights[i];
+        const double middle_z = 0.5 * (top_z + bottom_z);
+        const double width = widths[i];
+
+        const bool is_first = (ii == 0);
+        const bool is_last = (ii == lines_end - 1);
+        const bool is_closing = closed && is_last;
+
+        const Vec2d v = unscale(line.vector()).normalized();
+        const double len = unscale<double>(line.length());
+
+        const Vec2d a = unscale(line.a);
+        const Vec2d b = unscale(line.b);
+        Vec2d a1 = a;
+        Vec2d a2 = a;
+        Vec2d b1 = b;
+        Vec2d b2 = b;
+        {
+            const double dist = 0.5 * width;  // scaled
+            const double dx = dist * v.x();
+            const double dy = dist * v.y();
+            a1 += Vec2d(+dy, -dx);
+            a2 += Vec2d(-dy, +dx);
+            b1 += Vec2d(+dy, -dx);
+            b2 += Vec2d(-dy, +dx);
+        }
+
+        // calculate new XY normals
+        const Vec2d xy_right_normal = unscale(line.normal()).normalized();
+
+        std::array<int, 4> idx_a = { 0, 0, 0, 0 };
+        std::array<int, 4> idx_b = { 0, 0, 0, 0 };
+        int idx_last = int(geometry.vertices_count());
+
+        const bool bottom_z_different = bottom_z_prev != bottom_z;
+        bottom_z_prev = bottom_z;
+
+        if (!is_first && bottom_z_different) {
+            // Found a change of the layer thickness -> Add a cap at the end of the previous segment.
+            geometry.add_uint_triangle(idx_b[Bottom], idx_b[Left], idx_b[Top]);
+            geometry.add_uint_triangle(idx_b[Bottom], idx_b[Top], idx_b[Right]);
+        }
+
+        // Share top / bottom vertices if possible.
+        if (is_first) {
+            idx_a[Top] = idx_last++;
+            geometry.add_vertex(Vec3f(a.x(), a.y(), top_z), Vec3f(0.0f, 0.0f, 1.0f));
+        }
+        else
+            idx_a[Top] = idx_prev[Top];
+
+        if (is_first || bottom_z_different) {
+            // Start of the 1st line segment or a change of the layer thickness while maintaining the print_z.
+            idx_a[Bottom] = idx_last++;
+            geometry.add_vertex(Vec3f(a.x(), a.y(), bottom_z), Vec3f(0.0f, 0.0f, -1.0f));
+            idx_a[Left] = idx_last++;
+            geometry.add_vertex(Vec3f(a2.x(), a2.y(), middle_z), Vec3f(-xy_right_normal.x(), -xy_right_normal.y(), 0.0f));
+            idx_a[Right] = idx_last++;
+            geometry.add_vertex(Vec3f(a1.x(), a1.y(), middle_z), Vec3f(xy_right_normal.x(), xy_right_normal.y(), 0.0f));
+        }
+        else
+            idx_a[Bottom] = idx_prev[Bottom];
+
+        if (is_first) {
+            // Start of the 1st line segment.
+            width_initial = width;
+            bottom_z_initial = bottom_z;
+            idx_initial = idx_a;
+        }
+        else {
+            // Continuing a previous segment.
+            // Share left / right vertices if possible.
+            const double v_dot = v_prev.dot(v);
+            // To reduce gpu memory usage, we try to reuse vertices
+            // To reduce the visual artifacts, due to averaged normals, we allow to reuse vertices only when any of two adjacent edges 
+            // is longer than a fixed threshold.
+            // The following value is arbitrary, it comes from tests made on a bunch of models showing the visual artifacts
+            const double len_threshold = 2.5;
+
+            // Generate new vertices if the angle between adjacent edges is greater than 45 degrees or thresholds conditions are met
+            const bool sharp = (v_dot < 0.707) || (len_prev > len_threshold) || (len > len_threshold);
+            if (sharp) {
+                if (!bottom_z_different) {
+                    // Allocate new left / right points for the start of this segment as these points will receive their own normals to indicate a sharp turn.
+                    idx_a[Right] = idx_last++;
+                    geometry.add_vertex(Vec3f(a1.x(), a1.y(), middle_z), Vec3f(xy_right_normal.x(), xy_right_normal.y(), 0.0f));
+                    idx_a[Left] = idx_last++;
+                    geometry.add_vertex(Vec3f(a2.x(), a2.y(), middle_z), Vec3f(-xy_right_normal.x(), -xy_right_normal.y(), 0.0f));
+                    if (cross2(v_prev, v) > 0.0) {
+                        // Right turn. Fill in the right turn wedge.
+                        geometry.add_uint_triangle(idx_prev[Right], idx_a[Right], idx_prev[Top]);
+                        geometry.add_uint_triangle(idx_prev[Right], idx_prev[Bottom], idx_a[Right]);
+                    }
+                    else {
+                        // Left turn. Fill in the left turn wedge.
+                        geometry.add_uint_triangle(idx_prev[Left], idx_prev[Top], idx_a[Left]);
+                        geometry.add_uint_triangle(idx_prev[Left], idx_a[Left], idx_prev[Bottom]);
+                    }
+                }
+            }
+            else {
+                if (!bottom_z_different) {
+                    // The two successive segments are nearly collinear.
+                    idx_a[Left]  = idx_prev[Left];
+                    idx_a[Right] = idx_prev[Right];
+                }
+            }
+            if (is_closing) {
+                if (!sharp) {
+                    if (!bottom_z_different) {
+                        // Closing a loop with smooth transition. Unify the closing left / right vertices.
+                        geometry.set_vertex(idx_initial[Left], geometry.extract_position_3(idx_prev[Left]), geometry.extract_normal_3(idx_prev[Left]));
+                        geometry.set_vertex(idx_initial[Right], geometry.extract_position_3(idx_prev[Right]), geometry.extract_normal_3(idx_prev[Right]));
+                        geometry.remove_vertex(geometry.vertices_count() - 1);
+                        geometry.remove_vertex(geometry.vertices_count() - 1);
+                        // Replace the left / right vertex indices to point to the start of the loop.
+                        const size_t indices_count = geometry.indices_count();
+                        for (size_t u = indices_count - 24; u < indices_count; ++u) {
+                            const unsigned int id = geometry.extract_uint_index(u);
+                            if (id == (unsigned int)idx_prev[Left])
+                                geometry.set_uint_index(u, (unsigned int)idx_initial[Left]);
+                            else if (id == (unsigned int)idx_prev[Right])
+                                geometry.set_uint_index(u, (unsigned int)idx_initial[Right]);
+                        }
+                    }
+                }
+                // This is the last iteration, only required to solve the transition.
+                break;
+            }
+        }
+
+        // Only new allocate top / bottom vertices, if not closing a loop.
+        if (is_closing)
+            idx_b[Top] = idx_initial[Top];
+        else {
+            idx_b[Top] = idx_last++;
+            geometry.add_vertex(Vec3f(b.x(), b.y(), top_z), Vec3f(0.0f, 0.0f, 1.0f));
+        }
+
+        if (is_closing && width == width_initial && bottom_z == bottom_z_initial)
+            idx_b[Bottom] = idx_initial[Bottom];
+        else {
+            idx_b[Bottom] = idx_last++;
+            geometry.add_vertex(Vec3f(b.x(), b.y(), bottom_z), Vec3f(0.0f, 0.0f, -1.0f));
+        }
+        // Generate new vertices for the end of this line segment.
+        idx_b[Left] = idx_last++;
+        geometry.add_vertex(Vec3f(b2.x(), b2.y(), middle_z), Vec3f(-xy_right_normal.x(), -xy_right_normal.y(), 0.0f));
+        idx_b[Right] = idx_last++;
+        geometry.add_vertex(Vec3f(b1.x(), b1.y(), middle_z), Vec3f(xy_right_normal.x(), xy_right_normal.y(), 0.0f));
+
+        idx_prev = idx_b;
+        bottom_z_prev = bottom_z;
+        b1_prev = b1;
+        v_prev = v;
+        len_prev = len;
+
+        if (bottom_z_different && (closed || (!is_first && !is_last))) {
+            // Found a change of the layer thickness -> Add a cap at the beginning of this segment.
+            geometry.add_uint_triangle(idx_a[Bottom], idx_a[Right], idx_a[Top]);
+            geometry.add_uint_triangle(idx_a[Bottom], idx_a[Top], idx_a[Left]);
+        }
+
+        if (!closed) {
+            // Terminate open paths with caps.
+            if (is_first) {
+                geometry.add_uint_triangle(idx_a[Bottom], idx_a[Right], idx_a[Top]);
+                geometry.add_uint_triangle(idx_a[Bottom], idx_a[Top], idx_a[Left]);
+            }
+            // We don't use 'else' because both cases are true if we have only one line.
+            if (is_last) {
+                geometry.add_uint_triangle(idx_b[Bottom], idx_b[Left], idx_b[Top]);
+                geometry.add_uint_triangle(idx_b[Bottom], idx_b[Top], idx_b[Right]);
+            }
+        }
+
+        // Add quads for a straight hollow tube-like segment.
+        // bottom-right face
+        geometry.add_uint_triangle(idx_a[Bottom], idx_b[Bottom], idx_b[Right]);
+        geometry.add_uint_triangle(idx_a[Bottom], idx_b[Right], idx_a[Right]);
+        // top-right face
+        geometry.add_uint_triangle(idx_a[Right], idx_b[Right], idx_b[Top]);
+        geometry.add_uint_triangle(idx_a[Right], idx_b[Top], idx_a[Top]);
+        // top-left face
+        geometry.add_uint_triangle(idx_a[Top], idx_b[Top], idx_b[Left]);
+        geometry.add_uint_triangle(idx_a[Top], idx_b[Left], idx_a[Left]);
+        // bottom-left face
+        geometry.add_uint_triangle(idx_a[Left], idx_b[Left], idx_b[Bottom]);
+        geometry.add_uint_triangle(idx_a[Left], idx_b[Bottom], idx_a[Bottom]);
+    }
+}
+
+// caller is responsible for supplying NO lines with zero length
+static void thick_lines_to_geometry(
+    const Lines3&              lines,
+    const std::vector<double>& widths,
+    const std::vector<double>& heights,
+    bool                       closed,
+    GUI::GLModel::Geometry&    geometry)
+{
+    assert(!lines.empty());
+    if (lines.empty())
+        return;
+
+    enum Direction : unsigned char
+    {
+        Left,
+        Right,
+        Top,
+        Bottom
+    };
+
+    // left, right, top, bottom
+    std::array<int, 4> idx_prev    = { -1, -1, -1, -1 };
+    std::array<int, 4> idx_initial = { -1, -1, -1, -1 };
+
+    double z_prev = 0.0;
+    double len_prev = 0.0;
+    Vec3d  n_right_prev = Vec3d::Zero();
+    Vec3d  n_top_prev = Vec3d::Zero();
+    Vec3d  unit_v_prev = Vec3d::Zero();
+    double width_initial = 0.0;
+
+    // new vertices around the line endpoints
+    // left, right, top, bottom
+    std::array<Vec3d, 4> a = { Vec3d::Zero(), Vec3d::Zero(), Vec3d::Zero(), Vec3d::Zero() };
+    std::array<Vec3d, 4> b = { Vec3d::Zero(), Vec3d::Zero(), Vec3d::Zero(), Vec3d::Zero() };
+
+    // loop once more in case of closed loops
+    const size_t lines_end = closed ? (lines.size() + 1) : lines.size();
+    for (size_t ii = 0; ii < lines_end; ++ii) {
+        const size_t i = (ii == lines.size()) ? 0 : ii;
+
+        const Line3& line = lines[i];
+        const double height = heights[i];
+        const double width = widths[i];
+
+        const Vec3d unit_v = unscale(line.vector()).normalized();
+        const double len = unscale<double>(line.length());
+
+        Vec3d n_top = Vec3d::Zero();
+        Vec3d n_right = Vec3d::Zero();
+
+        if (line.a.x() == line.b.x() && line.a.y() == line.b.y()) {
+            // vertical segment
+            n_top = Vec3d::UnitY();
+            n_right = Vec3d::UnitX();
+            if (line.a.z() < line.b.z())
+                n_right = -n_right;
+        }
+        else {
+            // horizontal segment
+            n_right = unit_v.cross(Vec3d::UnitZ()).normalized();
+            n_top = n_right.cross(unit_v).normalized();
+        }
+
+        const Vec3d rl_displacement = 0.5 * width * n_right;
+        const Vec3d tb_displacement = 0.5 * height * n_top;
+        const Vec3d l_a = unscale(line.a);
+        const Vec3d l_b = unscale(line.b);
+
+        a[Right]  = l_a + rl_displacement;
+        a[Left]   = l_a - rl_displacement;
+        a[Top]    = l_a + tb_displacement;
+        a[Bottom] = l_a - tb_displacement;
+        b[Right]  = l_b + rl_displacement;
+        b[Left]   = l_b - rl_displacement;
+        b[Top]    = l_b + tb_displacement;
+        b[Bottom] = l_b - tb_displacement;
+
+        const Vec3d n_bottom = -n_top;
+        const Vec3d n_left = -n_right;
+
+        std::array<int, 4> idx_a = { 0, 0, 0, 0};
+        std::array<int, 4> idx_b = { 0, 0, 0, 0 };
+        int idx_last = int(geometry.vertices_count());
+
+        const bool z_different = (z_prev != l_a.z());
+        z_prev = l_b.z();
+
+        // Share top / bottom vertices if possible.
+        if (ii == 0) {
+            idx_a[Top] = idx_last++;
+            geometry.add_vertex((Vec3f)a[Top].cast<float>(), (Vec3f)n_top.cast<float>());
+        }
+        else
+            idx_a[Top] = idx_prev[Top];
+
+        if (ii == 0 || z_different) {
+            // Start of the 1st line segment or a change of the layer thickness while maintaining the print_z.
+            idx_a[Bottom] = idx_last++;
+            geometry.add_vertex((Vec3f)a[Bottom].cast<float>(), (Vec3f)n_bottom.cast<float>());
+            idx_a[Left] = idx_last++;
+            geometry.add_vertex((Vec3f)a[Left].cast<float>(), (Vec3f)n_left.cast<float>());
+            idx_a[Right] = idx_last++;
+            geometry.add_vertex((Vec3f)a[Right].cast<float>(), (Vec3f)n_right.cast<float>());
+        }
+        else
+            idx_a[Bottom] = idx_prev[Bottom];
+
+        if (ii == 0) {
+            // Start of the 1st line segment.
+            width_initial = width;
+            idx_initial =  idx_a;
+        }
+        else {
+            // Continuing a previous segment.
+            // Share left / right vertices if possible.
+            const double v_dot = unit_v_prev.dot(unit_v);
+            const bool is_right_turn = n_top_prev.dot(unit_v_prev.cross(unit_v)) > 0.0;
+
+            // To reduce gpu memory usage, we try to reuse vertices
+            // To reduce the visual artifacts, due to averaged normals, we allow to reuse vertices only when any of two adjacent edges 
+            // is longer than a fixed threshold.
+            // The following value is arbitrary, it comes from tests made on a bunch of models showing the visual artifacts
+            const double len_threshold = 2.5;
+
+            // Generate new vertices if the angle between adjacent edges is greater than 45 degrees or thresholds conditions are met
+            const bool is_sharp = v_dot < 0.707 || len_prev > len_threshold || len > len_threshold;
+            if (is_sharp) {
+                // Allocate new left / right points for the start of this segment as these points will receive their own normals to indicate a sharp turn.
+                idx_a[Right] = idx_last++;
+                geometry.add_vertex((Vec3f)a[Right].cast<float>(), (Vec3f)n_right.cast<float>());
+                idx_a[Left] = idx_last++;
+                geometry.add_vertex((Vec3f)a[Left].cast<float>(), (Vec3f)n_left.cast<float>());
+
+                if (is_right_turn) {
+                    // Right turn. Fill in the right turn wedge.
+                    geometry.add_uint_triangle(idx_prev[Right], idx_a[Right], idx_prev[Top]);
+                    geometry.add_uint_triangle(idx_prev[Right], idx_prev[Bottom], idx_a[Right]);
+                }
+                else {
+                    // Left turn. Fill in the left turn wedge.
+                    geometry.add_uint_triangle(idx_prev[Left], idx_prev[Top], idx_a[Left]);
+                    geometry.add_uint_triangle(idx_prev[Left], idx_a[Left], idx_prev[Bottom]);
+                }
+            }
+            else {
+                // The two successive segments are nearly collinear.
+                idx_a[Left] = idx_prev[Left];
+                idx_a[Right] = idx_prev[Right];
+            }
+
+            if (ii == lines.size()) {
+                if (!is_sharp) {
+                    // Closing a loop with smooth transition. Unify the closing left / right vertices.
+                    geometry.set_vertex(idx_initial[Left], geometry.extract_position_3(idx_prev[Left]), geometry.extract_normal_3(idx_prev[Left]));
+                    geometry.set_vertex(idx_initial[Right], geometry.extract_position_3(idx_prev[Right]), geometry.extract_normal_3(idx_prev[Right]));
+                    geometry.remove_vertex(geometry.vertices_count() - 1);
+                    geometry.remove_vertex(geometry.vertices_count() - 1);
+                    // Replace the left / right vertex indices to point to the start of the loop.
+                    const size_t indices_count = geometry.indices_count();
+                    for (size_t u = indices_count - 24; u < indices_count; ++u) {
+                        const unsigned int id = geometry.extract_uint_index(u);
+                        if (id == (unsigned int)idx_prev[Left])
+                            geometry.set_uint_index(u, (unsigned int)idx_initial[Left]);
+                        else if (id == (unsigned int)idx_prev[Right])
+                            geometry.set_uint_index(u, (unsigned int)idx_initial[Right]);
+                    }
+                }
+
+                // This is the last iteration, only required to solve the transition.
+                break;
+            }
+        }
+
+        // Only new allocate top / bottom vertices, if not closing a loop.
+        if (closed && ii + 1 == lines.size())
+            idx_b[Top] = idx_initial[Top];
+        else {
+            idx_b[Top] = idx_last++;
+            geometry.add_vertex((Vec3f)b[Top].cast<float>(), (Vec3f)n_top.cast<float>());
+        }
+
+        if (closed && ii + 1 == lines.size() && width == width_initial)
+            idx_b[Bottom] = idx_initial[Bottom];
+        else {
+            idx_b[Bottom] = idx_last++;
+            geometry.add_vertex((Vec3f)b[Bottom].cast<float>(), (Vec3f)n_bottom.cast<float>());
+        }
+
+        // Generate new vertices for the end of this line segment.
+        idx_b[Left] = idx_last++;
+        geometry.add_vertex((Vec3f)b[Left].cast<float>(), (Vec3f)n_left.cast<float>());
+        idx_b[Right] = idx_last++;
+        geometry.add_vertex((Vec3f)b[Right].cast<float>(), (Vec3f)n_right.cast<float>());
+
+        idx_prev = idx_b;
+        n_right_prev = n_right;
+        n_top_prev = n_top;
+        unit_v_prev = unit_v;
+        len_prev = len;
+
+        if (!closed) {
+            // Terminate open paths with caps.
+            if (i == 0) {
+                geometry.add_uint_triangle(idx_a[Bottom], idx_a[Right], idx_a[Top]);
+                geometry.add_uint_triangle(idx_a[Bottom], idx_a[Top], idx_a[Left]);
+            }
+
+            // We don't use 'else' because both cases are true if we have only one line.
+            if (i + 1 == lines.size()) {
+                geometry.add_uint_triangle(idx_b[Bottom], idx_b[Left], idx_b[Top]);
+                geometry.add_uint_triangle(idx_b[Bottom], idx_b[Top], idx_b[Right]);
+            }
+        }
+
+        // Add quads for a straight hollow tube-like segment.
+        // bottom-right face
+        geometry.add_uint_triangle(idx_a[Bottom], idx_b[Bottom], idx_b[Right]);
+        geometry.add_uint_triangle(idx_a[Bottom], idx_b[Right], idx_a[Right]);
+        // top-right face
+        geometry.add_uint_triangle(idx_a[Right], idx_b[Right], idx_b[Top]);
+        geometry.add_uint_triangle(idx_a[Right], idx_b[Top], idx_a[Top]);
+        // top-left face
+        geometry.add_uint_triangle(idx_a[Top], idx_b[Top], idx_b[Left]);
+        geometry.add_uint_triangle(idx_a[Top], idx_b[Left], idx_a[Left]);
+        // bottom-left face
+        geometry.add_uint_triangle(idx_a[Left], idx_b[Left], idx_b[Bottom]);
+        geometry.add_uint_triangle(idx_a[Left], idx_b[Bottom], idx_a[Bottom]);
+    }
+}
+#else
 // caller is responsible for supplying NO lines with zero length
 static void thick_lines_to_indexed_vertex_array(
     const Lines                 &lines, 
@@ -1724,7 +2320,30 @@ static void point_to_indexed_vertex_array(const Vec3crd& point,
     volume.push_triangle(idxs[3], idxs[1], idxs[4]);
     volume.push_triangle(idxs[0], idxs[3], idxs[4]);
 }
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
 
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+void _3DScene::thick_lines_to_verts(
+    const Lines&               lines,
+    const std::vector<double>& widths,
+    const std::vector<double>& heights,
+    bool                       closed,
+    double                     top_z,
+    GUI::GLModel::Geometry&    geometry)
+{
+    thick_lines_to_geometry(lines, widths, heights, closed, top_z, geometry);
+}
+
+void _3DScene::thick_lines_to_verts(
+    const Lines3&              lines,
+    const std::vector<double>& widths,
+    const std::vector<double>& heights,
+    bool                       closed,
+    GUI::GLModel::Geometry&    geometry)
+{
+    thick_lines_to_geometry(lines, widths, heights, closed, geometry);
+}
+#else
 void _3DScene::thick_lines_to_verts(
     const Lines                 &lines,
     const std::vector<double>   &widths,
@@ -1766,8 +2385,21 @@ void _3DScene::extrusionentity_to_verts(const ExtrusionPath &extrusion_path, flo
 {
 	extrusionentity_to_verts(extrusion_path.polyline, extrusion_path.width, extrusion_path.height, print_z, volume);
 }
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
 
 // Fill in the qverts and tverts with quads and triangles for the extrusion_path.
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+void _3DScene::extrusionentity_to_verts(const ExtrusionPath& extrusion_path, float print_z, const Point& copy, GUI::GLModel::Geometry& geometry)
+{
+    Polyline            polyline = extrusion_path.polyline;
+    polyline.remove_duplicate_points();
+    polyline.translate(copy);
+    const Lines               lines = polyline.lines();
+    std::vector<double> widths(lines.size(), extrusion_path.width);
+    std::vector<double> heights(lines.size(), extrusion_path.height);
+    thick_lines_to_verts(lines, widths, heights, false, print_z, geometry);
+}
+#else
 void _3DScene::extrusionentity_to_verts(const ExtrusionPath &extrusion_path, float print_z, const Point &copy, GLVolume &volume)
 {
     Polyline            polyline = extrusion_path.polyline;
@@ -1778,8 +2410,27 @@ void _3DScene::extrusionentity_to_verts(const ExtrusionPath &extrusion_path, flo
     std::vector<double> heights(lines.size(), extrusion_path.height);
     thick_lines_to_verts(lines, widths, heights, false, print_z, volume);
 }
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
 
 // Fill in the qverts and tverts with quads and triangles for the extrusion_loop.
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+void _3DScene::extrusionentity_to_verts(const ExtrusionLoop& extrusion_loop, float print_z, const Point& copy, GUI::GLModel::Geometry& geometry)
+{
+    Lines               lines;
+    std::vector<double> widths;
+    std::vector<double> heights;
+    for (const ExtrusionPath& extrusion_path : extrusion_loop.paths) {
+        Polyline            polyline = extrusion_path.polyline;
+        polyline.remove_duplicate_points();
+        polyline.translate(copy);
+        const Lines lines_this = polyline.lines();
+        append(lines, lines_this);
+        widths.insert(widths.end(), lines_this.size(), extrusion_path.width);
+        heights.insert(heights.end(), lines_this.size(), extrusion_path.height);
+    }
+    thick_lines_to_verts(lines, widths, heights, true, print_z, geometry);
+}
+#else
 void _3DScene::extrusionentity_to_verts(const ExtrusionLoop &extrusion_loop, float print_z, const Point &copy, GLVolume &volume)
 {
     Lines               lines;
@@ -1796,8 +2447,27 @@ void _3DScene::extrusionentity_to_verts(const ExtrusionLoop &extrusion_loop, flo
     }
     thick_lines_to_verts(lines, widths, heights, true, print_z, volume);
 }
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
 
 // Fill in the qverts and tverts with quads and triangles for the extrusion_multi_path.
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+void _3DScene::extrusionentity_to_verts(const ExtrusionMultiPath& extrusion_multi_path, float print_z, const Point& copy, GUI::GLModel::Geometry& geometry)
+{
+    Lines               lines;
+    std::vector<double> widths;
+    std::vector<double> heights;
+    for (const ExtrusionPath& extrusion_path : extrusion_multi_path.paths) {
+        Polyline            polyline = extrusion_path.polyline;
+        polyline.remove_duplicate_points();
+        polyline.translate(copy);
+        const Lines lines_this = polyline.lines();
+        append(lines, lines_this);
+        widths.insert(widths.end(), lines_this.size(), extrusion_path.width);
+        heights.insert(heights.end(), lines_this.size(), extrusion_path.height);
+    }
+    thick_lines_to_verts(lines, widths, heights, false, print_z, geometry);
+}
+#else
 void _3DScene::extrusionentity_to_verts(const ExtrusionMultiPath &extrusion_multi_path, float print_z, const Point &copy, GLVolume &volume)
 {
     Lines               lines;
@@ -1814,13 +2484,49 @@ void _3DScene::extrusionentity_to_verts(const ExtrusionMultiPath &extrusion_mult
     }
     thick_lines_to_verts(lines, widths, heights, false, print_z, volume);
 }
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
 
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+void _3DScene::extrusionentity_to_verts(const ExtrusionEntityCollection& extrusion_entity_collection, float print_z, const Point& copy, GUI::GLModel::Geometry& geometry)
+{
+    for (const ExtrusionEntity* extrusion_entity : extrusion_entity_collection.entities)
+        extrusionentity_to_verts(extrusion_entity, print_z, copy, geometry);
+}
+#else
 void _3DScene::extrusionentity_to_verts(const ExtrusionEntityCollection &extrusion_entity_collection, float print_z, const Point &copy, GLVolume &volume)
 {
     for (const ExtrusionEntity *extrusion_entity : extrusion_entity_collection.entities)
         extrusionentity_to_verts(extrusion_entity, print_z, copy, volume);
 }
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
 
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+void _3DScene::extrusionentity_to_verts(const ExtrusionEntity* extrusion_entity, float print_z, const Point& copy, GUI::GLModel::Geometry& geometry)
+{
+    if (extrusion_entity != nullptr) {
+        auto* extrusion_path = dynamic_cast<const ExtrusionPath*>(extrusion_entity);
+        if (extrusion_path != nullptr)
+            extrusionentity_to_verts(*extrusion_path, print_z, copy, geometry);
+        else {
+            auto* extrusion_loop = dynamic_cast<const ExtrusionLoop*>(extrusion_entity);
+            if (extrusion_loop != nullptr)
+                extrusionentity_to_verts(*extrusion_loop, print_z, copy, geometry);
+            else {
+                auto* extrusion_multi_path = dynamic_cast<const ExtrusionMultiPath*>(extrusion_entity);
+                if (extrusion_multi_path != nullptr)
+                    extrusionentity_to_verts(*extrusion_multi_path, print_z, copy, geometry);
+                else {
+                    auto* extrusion_entity_collection = dynamic_cast<const ExtrusionEntityCollection*>(extrusion_entity);
+                    if (extrusion_entity_collection != nullptr)
+                        extrusionentity_to_verts(*extrusion_entity_collection, print_z, copy, geometry);
+                    else
+                        throw Slic3r::RuntimeError("Unexpected extrusion_entity type in to_verts()");
+                }
+            }
+        }
+    }
+}
+#else
 void _3DScene::extrusionentity_to_verts(const ExtrusionEntity *extrusion_entity, float print_z, const Point &copy, GLVolume &volume)
 {
     if (extrusion_entity != nullptr) {
@@ -1839,9 +2545,8 @@ void _3DScene::extrusionentity_to_verts(const ExtrusionEntity *extrusion_entity,
                     auto *extrusion_entity_collection = dynamic_cast<const ExtrusionEntityCollection*>(extrusion_entity);
                     if (extrusion_entity_collection != nullptr)
                         extrusionentity_to_verts(*extrusion_entity_collection, print_z, copy, volume);
-                    else {
+                    else
                         throw Slic3r::RuntimeError("Unexpected extrusion_entity type in to_verts()");
-                    }
                 }
             }
         }
@@ -1860,5 +2565,6 @@ void _3DScene::point3_to_verts(const Vec3crd& point, double width, double height
 {
     thick_point_to_verts(point, width, height, volume);
 }
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
 
 } // namespace Slic3r
diff --git a/src/slic3r/GUI/3DScene.hpp b/src/slic3r/GUI/3DScene.hpp
index c2e4e587c..ed2aa804e 100644
--- a/src/slic3r/GUI/3DScene.hpp
+++ b/src/slic3r/GUI/3DScene.hpp
@@ -46,6 +46,7 @@ enum ModelInstanceEPrintVolumeState : unsigned char;
 // Return appropriate color based on the ModelVolume.
 extern ColorRGBA color_from_model_volume(const ModelVolume& model_volume);
 
+#if !ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
 // A container for interleaved arrays of 3D vertices and normals,
 // possibly indexed by triangles and / or quads.
 class GLIndexedVertexArray {
@@ -246,6 +247,7 @@ public:
 private:
     BoundingBox m_bounding_box;
 };
+#endif // !ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
 
 class GLVolume {
 public:
@@ -388,11 +390,17 @@ public:
     // Is mouse or rectangle selection over this object to select/deselect it ?
     EHoverState         	hover;
 
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+    GUI::GLModel            model;
+#else
     // Interleaved triangles & normals with indexed triangles & quads.
     GLIndexedVertexArray        indexed_vertex_array;
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
     // Ranges of triangle and quad indices to be rendered.
     std::pair<size_t, size_t>   tverts_range;
+#if !ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
     std::pair<size_t, size_t>   qverts_range;
+#endif // !ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
 
     // If the qverts or tverts contain thick extrusions, then offsets keeps pointers of the starts
     // of the extrusions per layer.
@@ -402,13 +410,17 @@ public:
 
     // Bounding box of this volume, in unscaled coordinates.
     BoundingBoxf3 bounding_box() const { 
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+        return this->model.get_bounding_box();
+#else
         BoundingBoxf3 out;
-        if (! this->indexed_vertex_array.bounding_box().isEmpty()) {
+        if (!this->indexed_vertex_array.bounding_box().isEmpty()) {
             out.min = this->indexed_vertex_array.bounding_box().min().cast<double>();
             out.max = this->indexed_vertex_array.bounding_box().max().cast<double>();
             out.defined = true;
-        };
+        }
         return out;
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
     }
 
     void set_color(const ColorRGBA& rgba)        { color = rgba; }
@@ -498,14 +510,20 @@ public:
     // convex hull
     const TriangleMesh*  convex_hull() const { return m_convex_hull.get(); }
 
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+    bool                empty() const { return this->model.is_empty(); }
+#else
     bool                empty() const { return this->indexed_vertex_array.empty(); }
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
 
     void                set_range(double low, double high);
 
-    void                render() const;
+    void                render();
 
+#if !ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
     void                finalize_geometry(bool opengl_initialized) { this->indexed_vertex_array.finalize_geometry(opengl_initialized); }
     void                release_geometry() { this->indexed_vertex_array.release_geometry(); }
+#endif // !ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
 
     void                set_bounding_boxes_as_dirty() {
         m_transformed_bounding_box.reset();
@@ -524,12 +542,20 @@ public:
 #endif // ENABLE_SHOW_NON_MANIFOLD_EDGES
 
     // Return an estimate of the memory consumed by this class.
-    size_t 				cpu_memory_used() const { 
-    	//FIXME what to do wih m_convex_hull?
+    size_t 				cpu_memory_used() const {
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+        return sizeof(*this) + this->model.cpu_memory_used() + this->print_zs.capacity() * sizeof(coordf_t) +
+               this->offsets.capacity() * sizeof(size_t);
+    }
+    // Return an estimate of the memory held by GPU vertex buffers.
+    size_t 				gpu_memory_used() const { return this->model.gpu_memory_used(); }
+#else
+        //FIXME what to do wih m_convex_hull?
     	return sizeof(*this) - sizeof(this->indexed_vertex_array) + this->indexed_vertex_array.cpu_memory_used() + this->print_zs.capacity() * sizeof(coordf_t) + this->offsets.capacity() * sizeof(size_t);
     }
     // Return an estimate of the memory held by GPU vertex buffers.
     size_t 				gpu_memory_used() const { return this->indexed_vertex_array.gpu_memory_used(); }
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
     size_t 				total_memory_used() const { return this->cpu_memory_used() + this->gpu_memory_used(); }
 };
 
@@ -589,6 +615,36 @@ public:
     GLVolumeCollection() { set_default_slope_normal_z(); }
     ~GLVolumeCollection() { clear(); }
 
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+    std::vector<int> load_object(
+        const ModelObject* model_object,
+        int                      obj_idx,
+        const std::vector<int>& instance_idxs);
+
+    int load_object_volume(
+        const ModelObject* model_object,
+        int                obj_idx,
+        int                volume_idx,
+        int                instance_idx);
+
+    // Load SLA auxiliary GLVolumes (for support trees or pad).
+    void load_object_auxiliary(
+        const SLAPrintObject* print_object,
+        int                             obj_idx,
+        // pairs of <instance_idx, print_instance_idx>
+        const std::vector<std::pair<size_t, size_t>>& instances,
+        SLAPrintObjectStep              milestone,
+        // Timestamp of the last change of the milestone
+        size_t                          timestamp);
+
+#if ENABLE_WIPETOWER_OBJECTID_1000_REMOVAL
+    int load_wipe_tower_preview(
+        float pos_x, float pos_y, float width, float depth, float height, float rotation_angle, bool size_unknown, float brim_width);
+#else
+    int load_wipe_tower_preview(
+        int obj_idx, float pos_x, float pos_y, float width, float depth, float height, float rotation_angle, bool size_unknown, float brim_width);
+#endif // ENABLE_WIPETOWER_OBJECTID_1000_REMOVAL
+#else
     std::vector<int> load_object(
         const ModelObject 		*model_object,
         int                      obj_idx,
@@ -620,13 +676,20 @@ public:
     int load_wipe_tower_preview(
         int obj_idx, float pos_x, float pos_y, float width, float depth, float height, float rotation_angle, bool size_unknown, float brim_width, bool opengl_initialized);
 #endif // ENABLE_WIPETOWER_OBJECTID_1000_REMOVAL
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
 
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+    GLVolume* new_toolpath_volume(const ColorRGBA& rgba);
+    GLVolume* new_nontoolpath_volume(const ColorRGBA& rgba);
+#else
     GLVolume* new_toolpath_volume(const ColorRGBA& rgba, size_t reserve_vbo_floats = 0);
     GLVolume* new_nontoolpath_volume(const ColorRGBA& rgba, size_t reserve_vbo_floats = 0);
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
 
     // Render the volumes by OpenGL.
     void render(ERenderType type, bool disable_cullface, const Transform3d& view_matrix, std::function<bool(const GLVolume&)> filter_func = std::function<bool(const GLVolume&)>()) const;
 
+#if !ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
     // Finalize the initialization of the geometry & indices,
     // upload the geometry and indices to OpenGL VBO objects
     // and shrink the allocated data, possibly relasing it if it has been loaded into the VBOs.
@@ -634,11 +697,12 @@ public:
     // Release the geometry data assigned to the volumes.
     // If OpenGL VBOs were allocated, an OpenGL context has to be active to release them.
     void release_geometry() { for (auto *v : volumes) v->release_geometry(); }
+#endif // !ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
     // Clear the geometry
     void clear() { for (auto *v : volumes) delete v; volumes.clear(); }
 
     bool empty() const { return volumes.empty(); }
-    void set_range(double low, double high) { for (GLVolume *vol : this->volumes) vol->set_range(low, high); }
+    void set_range(double low, double high) { for (GLVolume* vol : this->volumes) vol->set_range(low, high); }
 
     void set_print_volume(const PrintVolume& print_volume) { m_print_volume = print_volume; }
 
@@ -683,9 +747,18 @@ GLVolumeWithIdAndZList volumes_to_render(const GLVolumePtrs& volumes, GLVolumeCo
 
 struct _3DScene
 {
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+    static void thick_lines_to_verts(const Lines& lines, const std::vector<double>& widths, const std::vector<double>& heights, bool closed, double top_z, GUI::GLModel::Geometry& geometry);
+    static void thick_lines_to_verts(const Lines3& lines, const std::vector<double>& widths, const std::vector<double>& heights, bool closed, GUI::GLModel::Geometry& geometry);
+    static void extrusionentity_to_verts(const ExtrusionPath& extrusion_path, float print_z, const Point& copy, GUI::GLModel::Geometry& geometry);
+    static void extrusionentity_to_verts(const ExtrusionLoop& extrusion_loop, float print_z, const Point& copy, GUI::GLModel::Geometry& geometry);
+    static void extrusionentity_to_verts(const ExtrusionMultiPath& extrusion_multi_path, float print_z, const Point& copy, GUI::GLModel::Geometry& geometry);
+    static void extrusionentity_to_verts(const ExtrusionEntityCollection& extrusion_entity_collection, float print_z, const Point& copy, GUI::GLModel::Geometry& geometry);
+    static void extrusionentity_to_verts(const ExtrusionEntity* extrusion_entity, float print_z, const Point& copy, GUI::GLModel::Geometry& geometry);
+#else
     static void thick_lines_to_verts(const Lines& lines, const std::vector<double>& widths, const std::vector<double>& heights, bool closed, double top_z, GLVolume& volume);
     static void thick_lines_to_verts(const Lines3& lines, const std::vector<double>& widths, const std::vector<double>& heights, bool closed, GLVolume& volume);
-	static void extrusionentity_to_verts(const Polyline &polyline, float width, float height, float print_z, GLVolume& volume);
+    static void extrusionentity_to_verts(const Polyline& polyline, float width, float height, float print_z, GLVolume& volume);
     static void extrusionentity_to_verts(const ExtrusionPath& extrusion_path, float print_z, GLVolume& volume);
     static void extrusionentity_to_verts(const ExtrusionPath& extrusion_path, float print_z, const Point& copy, GLVolume& volume);
     static void extrusionentity_to_verts(const ExtrusionLoop& extrusion_loop, float print_z, const Point& copy, GLVolume& volume);
@@ -694,6 +767,7 @@ struct _3DScene
     static void extrusionentity_to_verts(const ExtrusionEntity* extrusion_entity, float print_z, const Point& copy, GLVolume& volume);
     static void polyline3_to_verts(const Polyline3& polyline, double width, double height, GLVolume& volume);
     static void point3_to_verts(const Vec3crd& point, double width, double height, GLVolume& volume);
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
 };
 
 }
diff --git a/src/slic3r/GUI/GCodeViewer.cpp b/src/slic3r/GUI/GCodeViewer.cpp
index c86d16a1f..cfe6fe418 100644
--- a/src/slic3r/GUI/GCodeViewer.cpp
+++ b/src/slic3r/GUI/GCodeViewer.cpp
@@ -711,7 +711,11 @@ void GCodeViewer::init()
     m_gl_data_initialized = true;
 }
 
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+void GCodeViewer::load(const GCodeProcessorResult& gcode_result, const Print& print)
+#else
 void GCodeViewer::load(const GCodeProcessorResult& gcode_result, const Print& print, bool initialized)
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
 {
     // avoid processing if called with the same gcode_result
 #if ENABLE_VOLUMETRIC_RATE_TOOLPATHS_RECALC
@@ -750,7 +754,11 @@ void GCodeViewer::load(const GCodeProcessorResult& gcode_result, const Print& pr
     m_filament_densities = gcode_result.filament_densities;
 
     if (wxGetApp().is_editor())
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+        load_shells(print);
+#else
         load_shells(print, initialized);
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
     else {
         Pointfs bed_shape;
         std::string texture;
@@ -2289,7 +2297,11 @@ void GCodeViewer::load_toolpaths(const GCodeProcessorResult& gcode_result)
         progress_dialog->Destroy();
 }
 
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+void GCodeViewer::load_shells(const Print& print)
+#else
 void GCodeViewer::load_shells(const Print& print, bool initialized)
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
 {
     if (print.objects().empty())
         // no shells, return
@@ -2306,7 +2318,11 @@ void GCodeViewer::load_shells(const Print& print, bool initialized)
         }
 
         size_t current_volumes_count = m_shells.volumes.volumes.size();
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+        m_shells.volumes.load_object(model_obj, object_id, instance_ids);
+#else
         m_shells.volumes.load_object(model_obj, object_id, instance_ids, initialized);
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
 
         // adjust shells' z if raft is present
         const SlicingParameters& slicing_parameters = obj->slicing_parameters();
@@ -2330,6 +2346,15 @@ void GCodeViewer::load_shells(const Print& print, bool initialized)
             const float depth = print.wipe_tower_data(extruders_count).depth;
             const float brim_width = print.wipe_tower_data(extruders_count).brim_width;
 
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+#if ENABLE_WIPETOWER_OBJECTID_1000_REMOVAL
+            m_shells.volumes.load_wipe_tower_preview(config.wipe_tower_x, config.wipe_tower_y, config.wipe_tower_width, depth, max_z, config.wipe_tower_rotation_angle,
+                !print.is_step_done(psWipeTower), brim_width);
+#else
+            m_shells.volumes.load_wipe_tower_preview(1000, config.wipe_tower_x, config.wipe_tower_y, config.wipe_tower_width, depth, max_z, config.wipe_tower_rotation_angle,
+                !print.is_step_done(psWipeTower), brim_width);
+#endif // ENABLE_WIPETOWER_OBJECTID_1000_REMOVAL
+#else
 #if ENABLE_WIPETOWER_OBJECTID_1000_REMOVAL
             m_shells.volumes.load_wipe_tower_preview(config.wipe_tower_x, config.wipe_tower_y, config.wipe_tower_width, depth, max_z, config.wipe_tower_rotation_angle,
                 !print.is_step_done(psWipeTower), brim_width, initialized);
@@ -2337,6 +2362,7 @@ void GCodeViewer::load_shells(const Print& print, bool initialized)
             m_shells.volumes.load_wipe_tower_preview(1000, config.wipe_tower_x, config.wipe_tower_y, config.wipe_tower_width, depth, max_z, config.wipe_tower_rotation_angle,
                 !print.is_step_done(psWipeTower), brim_width, initialized);
 #endif // ENABLE_WIPETOWER_OBJECTID_1000_REMOVAL
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
         }
     }
 
@@ -3199,6 +3225,7 @@ void GCodeViewer::render_shells()
     if (shader == nullptr)
         return;
 
+#if !ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
     // when the background processing is enabled, it may happen that the shells data have been loaded
     // before opengl has been initialized for the preview canvas.
     // when this happens, the volumes' data have not been sent to gpu yet.
@@ -3206,6 +3233,7 @@ void GCodeViewer::render_shells()
         if (!v->indexed_vertex_array.has_VBOs())
             v->finalize_geometry(true);
     }
+#endif // !ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
 
 //    glsafe(::glDepthMask(GL_FALSE));
 
diff --git a/src/slic3r/GUI/GCodeViewer.hpp b/src/slic3r/GUI/GCodeViewer.hpp
index b2b0626d5..bdb3ed983 100644
--- a/src/slic3r/GUI/GCodeViewer.hpp
+++ b/src/slic3r/GUI/GCodeViewer.hpp
@@ -823,7 +823,11 @@ public:
     void init();
 
     // extract rendering data from the given parameters
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+    void load(const GCodeProcessorResult& gcode_result, const Print& print);
+#else
     void load(const GCodeProcessorResult& gcode_result, const Print& print, bool initialized);
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
     // recalculate ranges in dependence of what is visible and sets tool/print colors
     void refresh(const GCodeProcessorResult& gcode_result, const std::vector<std::string>& str_tool_colors);
 #if ENABLE_PREVIEW_LAYOUT
@@ -883,7 +887,11 @@ public:
 
 private:
     void load_toolpaths(const GCodeProcessorResult& gcode_result);
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+    void load_shells(const Print& print);
+#else
     void load_shells(const Print& print, bool initialized);
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
 #if !ENABLE_PREVIEW_LAYOUT
     void refresh_render_paths(bool keep_sequential_current_first, bool keep_sequential_current_last) const;
 #endif // !ENABLE_PREVIEW_LAYOUT
diff --git a/src/slic3r/GUI/GLCanvas3D.cpp b/src/slic3r/GUI/GLCanvas3D.cpp
index edd62ce0a..93c3c848f 100644
--- a/src/slic3r/GUI/GLCanvas3D.cpp
+++ b/src/slic3r/GUI/GLCanvas3D.cpp
@@ -526,7 +526,7 @@ void GLCanvas3D::LayersEditing::render_volumes(const GLCanvas3D& canvas, const G
     glsafe(::glTexImage2D(GL_TEXTURE_2D, 1, GL_RGBA, half_w, half_h, 0, GL_RGBA, GL_UNSIGNED_BYTE, 0));
     glsafe(::glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, w, h, GL_RGBA, GL_UNSIGNED_BYTE, m_layers_texture.data.data()));
     glsafe(::glTexSubImage2D(GL_TEXTURE_2D, 1, 0, 0, half_w, half_h, GL_RGBA, GL_UNSIGNED_BYTE, m_layers_texture.data.data() + m_layers_texture.width * m_layers_texture.height * 4));
-    for (const GLVolume* glvolume : volumes.volumes) {
+    for (GLVolume* glvolume : volumes.volumes) {
         // Render the object using the layer editing shader and texture.
         if (!glvolume->is_active || glvolume->composite_id.object_id != this->last_object_id || glvolume->is_modifier)
             continue;
@@ -1192,9 +1192,11 @@ bool GLCanvas3D::init()
     if (m_main_toolbar.is_enabled())
         m_layers_editing.init();
 
+#if !ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
     // on linux the gl context is not valid until the canvas is not shown on screen
     // we defer the geometry finalization of volumes until the first call to render()
     m_volumes.finalize_geometry(true);
+#endif // !ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
 
     if (m_gizmos.is_enabled() && !m_gizmos.init())
         std::cout << "Unable to initialize gizmos: please, check that all the required textures are available" << std::endl;
@@ -1799,7 +1801,11 @@ std::vector<int> GLCanvas3D::load_object(const ModelObject& model_object, int ob
             instance_idxs.emplace_back(i);
         }
     }
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+    return m_volumes.load_object(&model_object, obj_idx, instance_idxs);
+#else
     return m_volumes.load_object(&model_object, obj_idx, instance_idxs, m_initialized);
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
 }
 
 std::vector<int> GLCanvas3D::load_object(const Model& model, int obj_idx)
@@ -2024,7 +2030,11 @@ void GLCanvas3D::reload_scene(bool refresh_immediately, bool force_full_scene_re
                     // Note the index of the loaded volume, so that we can reload the main model GLVolume with the hollowed mesh
                     // later in this function.
                     it->volume_idx = m_volumes.volumes.size();
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+                    m_volumes.load_object_volume(&model_object, obj_idx, volume_idx, instance_idx);
+#else
                     m_volumes.load_object_volume(&model_object, obj_idx, volume_idx, instance_idx, m_initialized);
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
                     m_volumes.volumes.back()->geometry_id = key.geometry_id;
                     update_object_list = true;
                 } else {
@@ -2081,31 +2091,55 @@ void GLCanvas3D::reload_scene(bool refresh_immediately, bool force_full_scene_re
                         GLVolume &volume = *m_volumes.volumes[it->volume_idx];
                         if (! volume.offsets.empty() && state.step[istep].timestamp != volume.offsets.front()) {
                         	// The backend either produced a new hollowed mesh, or it invalidated the one that the front end has seen.
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+                            volume.model.reset();
+#else
                             volume.indexed_vertex_array.release_geometry();
-                        	if (state.step[istep].state == PrintStateBase::DONE) {
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+                            if (state.step[istep].state == PrintStateBase::DONE) {
                                 TriangleMesh mesh = print_object->get_mesh(slaposDrillHoles);
 	                            assert(! mesh.empty());
                                 mesh.transform(sla_print->sla_trafo(*m_model->objects[volume.object_idx()]).inverse());
 #if ENABLE_SMOOTH_NORMALS
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+                                volume.model.init_from(mesh, true);
+#else
                                 volume.indexed_vertex_array.load_mesh(mesh, true);
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+#else
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+                                volume.model.init_from(mesh);
 #else
                                 volume.indexed_vertex_array.load_mesh(mesh);
-#endif // ENABLE_SMOOTH_NORMALS
-                            } else {
-	                        	// Reload the original volume.
-#if ENABLE_SMOOTH_NORMALS
-                                volume.indexed_vertex_array.load_mesh(m_model->objects[volume.object_idx()]->volumes[volume.volume_idx()]->mesh(), true);
-#else
-                                volume.indexed_vertex_array.load_mesh(m_model->objects[volume.object_idx()]->volumes[volume.volume_idx()]->mesh());
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
 #endif // ENABLE_SMOOTH_NORMALS
                             }
+                            else {
+	                        	// Reload the original volume.
+#if ENABLE_SMOOTH_NORMALS
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+                                volume.model.init_from(m_model->objects[volume.object_idx()]->volumes[volume.volume_idx()]->mesh(), true);
+#else
+                                volume.indexed_vertex_array.load_mesh(m_model->objects[volume.object_idx()]->volumes[volume.volume_idx()]->mesh(), true);
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+#else
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+                                volume.model.init_from(m_model->objects[volume.object_idx()]->volumes[volume.volume_idx()]->mesh());
+#else
+                                volume.indexed_vertex_array.load_mesh(m_model->objects[volume.object_idx()]->volumes[volume.volume_idx()]->mesh());
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+#endif // ENABLE_SMOOTH_NORMALS
+                            }
+#if !ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
                             volume.finalize_geometry(true);
-	                    }
+#endif // !ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+                        }
                     	//FIXME it is an ugly hack to write the timestamp into the "offsets" field to not have to add another member variable
                     	// to the GLVolume. We should refactor GLVolume significantly, so that the GLVolume will not contain member variables
                     	// of various concenrs (model vs. 3D print path).
                     	volume.offsets = { state.step[istep].timestamp };
-                    } else if (state.step[istep].state == PrintStateBase::DONE) {
+                    }
+                    else if (state.step[istep].state == PrintStateBase::DONE) {
                         // Check whether there is an existing auxiliary volume to be updated, or a new auxiliary volume to be created.
 						ModelVolumeState key(state.step[istep].timestamp, instance.instance_id.id);
 						auto it = std::lower_bound(aux_volume_state.begin(), aux_volume_state.end(), key, model_volume_state_lower);
@@ -2117,7 +2151,8 @@ void GLCanvas3D::reload_scene(bool refresh_immediately, bool force_full_scene_re
                                 instances[istep].emplace_back(std::pair<size_t, size_t>(instance_idx, print_instance_idx));
                             else
                                 shift_zs[object_idx] = 0.;
-                        } else {
+                        }
+                        else {
                             // Recycling an old GLVolume. Update the Object/Instance indices into the current Model.
                             m_volumes.volumes[it->volume_idx]->composite_id = GLVolume::CompositeID(object_idx, m_volumes.volumes[it->volume_idx]->volume_idx(), instance_idx);
                             m_volumes.volumes[it->volume_idx]->set_instance_transformation(model_object->instances[instance_idx]->get_transformation());
@@ -2127,7 +2162,11 @@ void GLCanvas3D::reload_scene(bool refresh_immediately, bool force_full_scene_re
 
             for (size_t istep = 0; istep < sla_steps.size(); ++istep)
                 if (!instances[istep].empty())
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+                    m_volumes.load_object_auxiliary(print_object, object_idx, instances[istep], sla_steps[istep], state.step[istep].timestamp);
+#else
                     m_volumes.load_object_auxiliary(print_object, object_idx, instances[istep], sla_steps[istep], state.step[istep].timestamp, m_initialized);
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
         }
 
 		// Shift-up all volumes of the object so that it has the right elevation with respect to the print bed
@@ -2157,6 +2196,17 @@ void GLCanvas3D::reload_scene(bool refresh_immediately, bool force_full_scene_re
             float depth = print->wipe_tower_data(extruders_count).depth;
             float brim_width = print->wipe_tower_data(extruders_count).brim_width;
 
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+#if ENABLE_WIPETOWER_OBJECTID_1000_REMOVAL
+            int volume_idx_wipe_tower_new = m_volumes.load_wipe_tower_preview(
+                x, y, w, depth, (float)height, a, !print->is_step_done(psWipeTower),
+                brim_width);
+#else
+            int volume_idx_wipe_tower_new = m_volumes.load_wipe_tower_preview(
+                1000, x, y, w, depth, (float)height, a, !print->is_step_done(psWipeTower),
+                brim_width);
+#endif // ENABLE_WIPETOWER_OBJECTID_1000_REMOVAL
+#else
 #if ENABLE_WIPETOWER_OBJECTID_1000_REMOVAL
             int volume_idx_wipe_tower_new = m_volumes.load_wipe_tower_preview(
                 x, y, w, depth, (float)height, a, !print->is_step_done(psWipeTower),
@@ -2166,6 +2216,7 @@ void GLCanvas3D::reload_scene(bool refresh_immediately, bool force_full_scene_re
                 1000, x, y, w, depth, (float)height, a, !print->is_step_done(psWipeTower),
                 brim_width, m_initialized);
 #endif // ENABLE_WIPETOWER_OBJECTID_1000_REMOVAL
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
             if (volume_idx_wipe_tower_old != -1)
                 map_glvolume_old_to_new[volume_idx_wipe_tower_old] = volume_idx_wipe_tower_new;
         }
@@ -2225,9 +2276,10 @@ void GLCanvas3D::reload_scene(bool refresh_immediately, bool force_full_scene_re
     m_dirty = true;
 }
 
+#if !ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
 static void reserve_new_volume_finalize_old_volume(GLVolume& vol_new, GLVolume& vol_old, bool gl_initialized, size_t prealloc_size = VERTEX_BUFFER_RESERVE_SIZE)
 {
-	// Assign the large pre-allocated buffers to the new GLVolume.
+    // Assign the large pre-allocated buffers to the new GLVolume.
 	vol_new.indexed_vertex_array = std::move(vol_old.indexed_vertex_array);
 	// Copy the content back to the old GLVolume.
 	vol_old.indexed_vertex_array = vol_new.indexed_vertex_array;
@@ -2239,10 +2291,15 @@ static void reserve_new_volume_finalize_old_volume(GLVolume& vol_new, GLVolume&
 	// Finalize the old geometry, possibly move data to the graphics card.
 	vol_old.finalize_geometry(gl_initialized);
 }
+#endif // !ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
 
 void GLCanvas3D::load_gcode_preview(const GCodeProcessorResult& gcode_result, const std::vector<std::string>& str_tool_colors)
 {
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+    m_gcode_viewer.load(gcode_result, *this->fff_print());
+#else
     m_gcode_viewer.load(gcode_result, *this->fff_print(), m_initialized);
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
 
     if (wxGetApp().is_editor()) {
         m_gcode_viewer.update_shells_color_by_extruder(m_config);
@@ -4356,7 +4413,11 @@ void GLCanvas3D::_render_thumbnail_internal(ThumbnailData& thumbnail_data, const
     shader->set_uniform("emission_factor", 0.0f);
 
     for (GLVolume* vol : visible_volumes) {
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+        vol->model.set_color((vol->printable && !vol->is_outside) ? (current_printer_technology() == ptSLA ? vol->color : ColorRGBA::ORANGE()) : ColorRGBA::GRAY());
+#else
         shader->set_uniform("uniform_color", (vol->printable && !vol->is_outside) ? (current_printer_technology() == ptSLA ? vol->color : ColorRGBA::ORANGE()) : ColorRGBA::GRAY());
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
         // the volume may have been deactivated by an active gizmo
         bool is_active = vol->is_active;
         vol->is_active = true;
@@ -5562,6 +5623,12 @@ void GLCanvas3D::_render_overlays()
 
 void GLCanvas3D::_render_volumes_for_picking() const
 {
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+    GLShaderProgram* shader = wxGetApp().get_shader("flat");
+    if (shader == nullptr)
+        return;
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+
     // do not cull backfaces to show broken geometry, if any
     glsafe(::glDisable(GL_CULL_FACE));
 
@@ -5577,9 +5644,17 @@ void GLCanvas3D::_render_volumes_for_picking() const
                 // we reserve color = (0,0,0) for occluders (as the printbed) 
                 // so we shift volumes' id by 1 to get the proper color
                 const unsigned int id = 1 + volume.second.first;
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+                volume.first->model.set_color(picking_decode(id));
+                shader->start_using();
+#else
                 glsafe(::glColor4fv(picking_decode(id).data()));
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
                 volume.first->render();
-	        }
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+                shader->stop_using();
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+            }
 	}
 
     glsafe(::glDisableClientState(GL_NORMAL_ARRAY));
@@ -6165,23 +6240,48 @@ void GLCanvas3D::_load_print_toolpaths(const BuildVolume &build_volume)
     skirt_height = std::min(skirt_height, print_zs.size());
     print_zs.erase(print_zs.begin() + skirt_height, print_zs.end());
 
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+    GLVolume* volume = m_volumes.new_toolpath_volume(color);
+    GLModel::Geometry init_data;
+    init_data.format = { GLModel::Geometry::EPrimitiveType::Triangles, GLModel::Geometry::EVertexLayout::P3N3, GLModel::Geometry::EIndexType::UINT };
+#else
     GLVolume *volume = m_volumes.new_toolpath_volume(color, VERTEX_BUFFER_RESERVE_SIZE);
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
     for (size_t i = 0; i < skirt_height; ++ i) {
         volume->print_zs.emplace_back(print_zs[i]);
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+        volume->offsets.emplace_back(init_data.indices_count());
+        if (i == 0)
+            _3DScene::extrusionentity_to_verts(print->brim(), print_zs[i], Point(0, 0), init_data);
+        _3DScene::extrusionentity_to_verts(print->skirt(), print_zs[i], Point(0, 0), init_data);
+#else
         volume->offsets.emplace_back(volume->indexed_vertex_array.quad_indices.size());
         volume->offsets.emplace_back(volume->indexed_vertex_array.triangle_indices.size());
         if (i == 0)
             _3DScene::extrusionentity_to_verts(print->brim(), print_zs[i], Point(0, 0), *volume);
         _3DScene::extrusionentity_to_verts(print->skirt(), print_zs[i], Point(0, 0), *volume);
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
         // Ensure that no volume grows over the limits. If the volume is too large, allocate a new one.
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+        if (init_data.vertices_size_bytes() > MAX_VERTEX_BUFFER_SIZE) {
+            volume->model.init_from(std::move(init_data));
+#else
         if (volume->indexed_vertex_array.vertices_and_normals_interleaved.size() > MAX_VERTEX_BUFFER_SIZE) {
-        	GLVolume &vol = *volume;
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+            GLVolume &vol = *volume;
             volume = m_volumes.new_toolpath_volume(vol.color);
+#if !ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
             reserve_new_volume_finalize_old_volume(*volume, vol, m_initialized);
+#endif // !ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
         }
     }
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+    volume->model.init_from(std::move(init_data));
+    volume->is_outside = !contains(build_volume, volume->model);
+#else
     volume->is_outside = ! build_volume.all_paths_inside_vertices_and_normals_interleaved(volume->indexed_vertex_array.vertices_and_normals_interleaved, volume->indexed_vertex_array.bounding_box());
     volume->indexed_vertex_array.finalize_geometry(m_initialized);
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
 }
 
 void GLCanvas3D::_load_print_object_toolpaths(const PrintObject& print_object, const BuildVolume& build_volume, const std::vector<std::string>& str_tool_colors, const std::vector<CustomGCode::Item>& color_print_values)
@@ -6353,7 +6453,12 @@ void GLCanvas3D::_load_print_object_toolpaths(const PrintObject& print_object, c
         // Allocate the volume before locking.
 		GLVolume *volume = new GLVolume(color);
 		volume->is_extrusion_path = true;
-    	tbb::spin_mutex::scoped_lock lock;
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+        // to prevent sending data to gpu (in the main thread) while
+        // editing the model geometry
+        volume->model.disable_render();
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+        tbb::spin_mutex::scoped_lock lock;
     	// Lock by ROII, so if the emplace_back() fails, the lock will be released.
         lock.acquire(new_volume_mutex);
         m_volumes.volumes.emplace_back(volume);
@@ -6365,31 +6470,57 @@ void GLCanvas3D::_load_print_object_toolpaths(const PrintObject& print_object, c
         tbb::blocked_range<size_t>(0, ctxt.layers.size(), grain_size),
         [&ctxt, &new_volume, is_selected_separate_extruder, this](const tbb::blocked_range<size_t>& range) {
         GLVolumePtrs 		vols;
-        auto                volume = [&ctxt, &vols](size_t layer_idx, int extruder, int feature) -> GLVolume& {
-            return *vols[ctxt.color_by_color_print()?
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+        std::vector<GLModel::Geometry> geometries;
+        auto select_geometry = [&ctxt, &geometries](size_t layer_idx, int extruder, int feature) -> GLModel::Geometry& {
+            return geometries[ctxt.color_by_color_print() ?
                 ctxt.color_print_color_idx_by_layer_idx_and_extruder(layer_idx, extruder) :
-				ctxt.color_by_tool() ? 
-					std::min<int>(ctxt.number_tools() - 1, std::max<int>(extruder - 1, 0)) : 
-					feature
-				];
+                ctxt.color_by_tool() ?
+                std::min<int>(ctxt.number_tools() - 1, std::max<int>(extruder - 1, 0)) :
+                feature
+            ];
         };
+#else
+        auto                volume = [&ctxt, &vols](size_t layer_idx, int extruder, int feature) -> GLVolume& {
+            return *vols[ctxt.color_by_color_print() ?
+                ctxt.color_print_color_idx_by_layer_idx_and_extruder(layer_idx, extruder) :
+                ctxt.color_by_tool() ?
+                std::min<int>(ctxt.number_tools() - 1, std::max<int>(extruder - 1, 0)) :
+                feature
+            ];
+        };
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
         if (ctxt.color_by_color_print() || ctxt.color_by_tool()) {
-            for (size_t i = 0; i < ctxt.number_tools(); ++i)
+            for (size_t i = 0; i < ctxt.number_tools(); ++i) {
                 vols.emplace_back(new_volume(ctxt.color_tool(i)));
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+                geometries.emplace_back(GLModel::Geometry());
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+            }
         }
-        else
+        else {
             vols = { new_volume(ctxt.color_perimeters()), new_volume(ctxt.color_infill()), new_volume(ctxt.color_support()) };
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+            geometries = { GLModel::Geometry(), GLModel::Geometry(), GLModel::Geometry() };
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+        }
+
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+        assert(vols.size() == geometries.size());
+        for (GLModel::Geometry& g : geometries) {
+            g.format = { GLModel::Geometry::EPrimitiveType::Triangles, GLModel::Geometry::EVertexLayout::P3N3, GLModel::Geometry::EIndexType::UINT };
+        }
+#else
         for (GLVolume *vol : vols)
 			// Reserving number of vertices (3x position + 3x color)
         	vol->indexed_vertex_array.reserve(VERTEX_BUFFER_RESERVE_SIZE / 6);
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
         for (size_t idx_layer = range.begin(); idx_layer < range.end(); ++ idx_layer) {
             const Layer *layer = ctxt.layers[idx_layer];
 
-            if (is_selected_separate_extruder)
-            {
+            if (is_selected_separate_extruder) {
                 bool at_least_one_has_correct_extruder = false;
-                for (const LayerRegion* layerm : layer->regions())
-                {
+                for (const LayerRegion* layerm : layer->regions()) {
                     if (layerm->slices.surfaces.empty())
                         continue;
                     const PrintRegionConfig& cfg = layerm->region().config();
@@ -6404,17 +6535,27 @@ void GLCanvas3D::_load_print_object_toolpaths(const PrintObject& print_object, c
                     continue;
             }
 
-            for (GLVolume *vol : vols)
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+            for (size_t i = 0; i < vols.size(); ++i) {
+                GLVolume* vol = vols[i];
+                if (vol->print_zs.empty() || vol->print_zs.back() != layer->print_z) {
+                    vol->print_zs.emplace_back(layer->print_z);
+                    vol->offsets.emplace_back(geometries[i].indices_count());
+                }
+            }
+#else
+            for (GLVolume* vol : vols)
                 if (vol->print_zs.empty() || vol->print_zs.back() != layer->print_z) {
                     vol->print_zs.emplace_back(layer->print_z);
                     vol->offsets.emplace_back(vol->indexed_vertex_array.quad_indices.size());
                     vol->offsets.emplace_back(vol->indexed_vertex_array.triangle_indices.size());
                 }
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+
             for (const PrintInstance &instance : *ctxt.shifted_copies) {
                 const Point &copy = instance.shift;
                 for (const LayerRegion *layerm : layer->regions()) {
-                    if (is_selected_separate_extruder)
-                    {
+                    if (is_selected_separate_extruder) {
                         const PrintRegionConfig& cfg = layerm->region().config();
                         if (cfg.perimeter_extruder.value    != m_selected_extruder ||
                             cfg.infill_extruder.value       != m_selected_extruder ||
@@ -6422,19 +6563,31 @@ void GLCanvas3D::_load_print_object_toolpaths(const PrintObject& print_object, c
                             continue;
                     }
                     if (ctxt.has_perimeters)
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+                        _3DScene::extrusionentity_to_verts(layerm->perimeters, float(layer->print_z), copy,
+                            select_geometry(idx_layer, layerm->region().config().perimeter_extruder.value, 0));
+#else
                         _3DScene::extrusionentity_to_verts(layerm->perimeters, float(layer->print_z), copy,
                         	volume(idx_layer, layerm->region().config().perimeter_extruder.value, 0));
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
                     if (ctxt.has_infill) {
                         for (const ExtrusionEntity *ee : layerm->fills.entities) {
                             // fill represents infill extrusions of a single island.
                             const auto *fill = dynamic_cast<const ExtrusionEntityCollection*>(ee);
                             if (! fill->entities.empty())
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+                                _3DScene::extrusionentity_to_verts(*fill, float(layer->print_z), copy,
+                                    select_geometry(idx_layer, is_solid_infill(fill->entities.front()->role()) ?
+                                                    layerm->region().config().solid_infill_extruder :
+                                                    layerm->region().config().infill_extruder, 1));
+#else
                                 _3DScene::extrusionentity_to_verts(*fill, float(layer->print_z), copy,
 	                                volume(idx_layer, 
 		                                is_solid_infill(fill->entities.front()->role()) ?
 			                                layerm->region().config().solid_infill_extruder :
 			                                layerm->region().config().infill_extruder,
 		                                1));
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
                         }
                     }
                 }
@@ -6442,28 +6595,50 @@ void GLCanvas3D::_load_print_object_toolpaths(const PrintObject& print_object, c
                     const SupportLayer *support_layer = dynamic_cast<const SupportLayer*>(layer);
                     if (support_layer) {
                         for (const ExtrusionEntity *extrusion_entity : support_layer->support_fills.entities)
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+                            _3DScene::extrusionentity_to_verts(extrusion_entity, float(layer->print_z), copy,
+                                select_geometry(idx_layer, (extrusion_entity->role() == erSupportMaterial) ?
+                                                support_layer->object()->config().support_material_extruder :
+                                                support_layer->object()->config().support_material_interface_extruder, 2));
+#else
                             _3DScene::extrusionentity_to_verts(extrusion_entity, float(layer->print_z), copy,
 	                            volume(idx_layer, 
 		                            (extrusion_entity->role() == erSupportMaterial) ?
 			                            support_layer->object()->config().support_material_extruder :
 			                            support_layer->object()->config().support_material_interface_extruder,
 		                            2));
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
                     }
                 }
             }
             // Ensure that no volume grows over the limits. If the volume is too large, allocate a new one.
 	        for (size_t i = 0; i < vols.size(); ++i) {
 	            GLVolume &vol = *vols[i];
-	            if (vol.indexed_vertex_array.vertices_and_normals_interleaved.size() > MAX_VERTEX_BUFFER_SIZE) {
-	                vols[i] = new_volume(vol.color);
-	                reserve_new_volume_finalize_old_volume(*vols[i], vol, false);
-	            }
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+                if (geometries[i].vertices_size_bytes() > MAX_VERTEX_BUFFER_SIZE) {
+                    vol.model.init_from(std::move(geometries[i]));
+#else
+                if (vol.indexed_vertex_array.vertices_and_normals_interleaved.size() > MAX_VERTEX_BUFFER_SIZE) {
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+                    vols[i] = new_volume(vol.color);
+#if !ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+                    reserve_new_volume_finalize_old_volume(*vols[i], vol, false);
+#endif // !ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+                }
 	        }
         }
+
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+        for (size_t i = 0; i < vols.size(); ++i) {
+            if (!geometries[i].is_empty())
+                vols[i]->model.init_from(std::move(geometries[i]));
+        }
+#else
         for (GLVolume *vol : vols)
         	// Ideally one would call vol->indexed_vertex_array.finalize() here to move the buffers to the OpenGL driver,
         	// but this code runs in parallel and the OpenGL driver is not thread safe.
             vol->indexed_vertex_array.shrink_to_fit();
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
     });
 
     BOOST_LOG_TRIVIAL(debug) << "Loading print object toolpaths in parallel - finalizing results" << m_volumes.log_memory_info() << log_memory_info();
@@ -6478,8 +6653,14 @@ void GLCanvas3D::_load_print_object_toolpaths(const PrintObject& print_object, c
     }
     for (size_t i = volumes_cnt_initial; i < m_volumes.volumes.size(); ++i) {
         GLVolume* v = m_volumes.volumes[i];
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+        v->is_outside = !contains(build_volume, v->model);
+        // We are done editinig the model, now it can be sent to gpu
+        v->model.enable_render();
+#else
         v->is_outside = ! build_volume.all_paths_inside_vertices_and_normals_interleaved(v->indexed_vertex_array.vertices_and_normals_interleaved, v->indexed_vertex_array.bounding_box());
         v->indexed_vertex_array.finalize_geometry(m_initialized);
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
     }
 
     BOOST_LOG_TRIVIAL(debug) << "Loading print object toolpaths in parallel - end" << m_volumes.log_memory_info() << log_memory_info();
@@ -6499,10 +6680,10 @@ void GLCanvas3D::_load_wipe_tower_toolpaths(const BuildVolume& build_volume, con
 
     struct Ctxt
     {
-        const Print                 *print;
-        const std::vector<ColorRGBA>* tool_colors;
-        Vec2f                        wipe_tower_pos;
-        float                        wipe_tower_angle;
+        const Print                  *print;
+        const std::vector<ColorRGBA> *tool_colors;
+        Vec2f                         wipe_tower_pos;
+        float                         wipe_tower_angle;
 
         static ColorRGBA color_support() { return ColorRGBA::GREENISH(); }
 
@@ -6544,6 +6725,11 @@ void GLCanvas3D::_load_wipe_tower_toolpaths(const BuildVolume& build_volume, con
     auto            new_volume = [this, &new_volume_mutex](const ColorRGBA& color) {
         auto *volume = new GLVolume(color);
 		volume->is_extrusion_path = true;
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+        // to prevent sending data to gpu (in the main thread) while
+        // editing the model geometry
+        volume->model.disable_render();
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
         tbb::spin_mutex::scoped_lock lock;
         lock.acquire(new_volume_mutex);
         m_volumes.volumes.emplace_back(volume);
@@ -6557,23 +6743,46 @@ void GLCanvas3D::_load_wipe_tower_toolpaths(const BuildVolume& build_volume, con
         [&ctxt, &new_volume](const tbb::blocked_range<size_t>& range) {
         // Bounding box of this slab of a wipe tower.
         GLVolumePtrs vols;
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+        std::vector<GLModel::Geometry> geometries;
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
         if (ctxt.color_by_tool()) {
-            for (size_t i = 0; i < ctxt.number_tools(); ++i)
+            for (size_t i = 0; i < ctxt.number_tools(); ++i) {
                 vols.emplace_back(new_volume(ctxt.color_tool(i)));
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+                geometries.emplace_back(GLModel::Geometry());
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+            }
         }
-        else
+        else {
             vols = { new_volume(ctxt.color_support()) };
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+            geometries = { GLModel::Geometry() };
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+        }
+
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+        assert(vols.size() == geometries.size());
+        for (GLModel::Geometry& g : geometries) {
+            g.format = { GLModel::Geometry::EPrimitiveType::Triangles, GLModel::Geometry::EVertexLayout::P3N3, GLModel::Geometry::EIndexType::UINT };
+        }
+#else
         for (GLVolume *volume : vols)
 			// Reserving number of vertices (3x position + 3x color)
             volume->indexed_vertex_array.reserve(VERTEX_BUFFER_RESERVE_SIZE / 6);
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
         for (size_t idx_layer = range.begin(); idx_layer < range.end(); ++idx_layer) {
             const std::vector<WipeTower::ToolChangeResult> &layer = ctxt.tool_change(idx_layer);
             for (size_t i = 0; i < vols.size(); ++i) {
                 GLVolume &vol = *vols[i];
                 if (vol.print_zs.empty() || vol.print_zs.back() != layer.front().print_z) {
                     vol.print_zs.emplace_back(layer.front().print_z);
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+                    vol.offsets.emplace_back(geometries[i].indices_count());
+#else
                     vol.offsets.emplace_back(vol.indexed_vertex_array.quad_indices.size());
                     vol.offsets.emplace_back(vol.indexed_vertex_array.triangle_indices.size());
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
                 }
             }
             for (const WipeTower::ToolChangeResult &extrusions : layer) {
@@ -6615,21 +6824,42 @@ void GLCanvas3D::_load_wipe_tower_toolpaths(const BuildVolume& build_volume, con
 
                         e_prev = e;
                     }
+
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+                    _3DScene::thick_lines_to_verts(lines, widths, heights, lines.front().a == lines.back().b, extrusions.print_z,
+                        geometries[ctxt.volume_idx(e.tool, 0)]);
+#else
                     _3DScene::thick_lines_to_verts(lines, widths, heights, lines.front().a == lines.back().b, extrusions.print_z,
                         *vols[ctxt.volume_idx(e.tool, 0)]);
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
                 }
             }
         }
         for (size_t i = 0; i < vols.size(); ++i) {
             GLVolume &vol = *vols[i];
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+            if (geometries[i].vertices_size_bytes() > MAX_VERTEX_BUFFER_SIZE) {
+                vol.model.init_from(std::move(geometries[i]));
+#else
             if (vol.indexed_vertex_array.vertices_and_normals_interleaved.size() > MAX_VERTEX_BUFFER_SIZE) {
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
                 vols[i] = new_volume(vol.color);
+#if !ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
                 reserve_new_volume_finalize_old_volume(*vols[i], vol, false);
+#endif // !ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
             }
         }
+
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+        for (size_t i = 0; i < vols.size(); ++i) {
+            if (!geometries[i].is_empty())
+                vols[i]->model.init_from(std::move(geometries[i]));
+        }
+#else
         for (GLVolume *vol : vols)
             vol->indexed_vertex_array.shrink_to_fit();
-    });
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+        });
 
     BOOST_LOG_TRIVIAL(debug) << "Loading wipe tower toolpaths in parallel - finalizing results" << m_volumes.log_memory_info() << log_memory_info();
     // Remove empty volumes from the newly added volumes.
@@ -6643,8 +6873,14 @@ void GLCanvas3D::_load_wipe_tower_toolpaths(const BuildVolume& build_volume, con
     }
     for (size_t i = volumes_cnt_initial; i < m_volumes.volumes.size(); ++i) {
         GLVolume* v = m_volumes.volumes[i];
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+        v->is_outside = !contains(build_volume, v->model);
+        // We are done editinig the model, now it can be sent to gpu
+        v->model.enable_render();
+#else
         v->is_outside = ! build_volume.all_paths_inside_vertices_and_normals_interleaved(v->indexed_vertex_array.vertices_and_normals_interleaved, v->indexed_vertex_array.bounding_box());
         v->indexed_vertex_array.finalize_geometry(m_initialized);
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
     }
 
     BOOST_LOG_TRIVIAL(debug) << "Loading wipe tower toolpaths in parallel - end" << m_volumes.log_memory_info() << log_memory_info();
@@ -6668,11 +6904,21 @@ void GLCanvas3D::_load_sla_shells()
         m_volumes.volumes.emplace_back(new GLVolume(color));
         GLVolume& v = *m_volumes.volumes.back();
 #if ENABLE_SMOOTH_NORMALS
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+        v.model.init_from(mesh, true);
+#else
         v.indexed_vertex_array.load_mesh(mesh, true);
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+#else
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+        v.model.init_from(mesh);
 #else
         v.indexed_vertex_array.load_mesh(mesh);
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
 #endif // ENABLE_SMOOTH_NORMALS
+#if !ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
         v.indexed_vertex_array.finalize_geometry(m_initialized);
+#endif // !ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
         v.shader_outside_printer_detection_enabled = outside_printer_detection_enabled;
         v.composite_id.volume_id = volume_id;
         v.set_instance_offset(unscale(instance.shift.x(), instance.shift.y(), 0.0));
diff --git a/src/slic3r/GUI/GLModel.cpp b/src/slic3r/GUI/GLModel.cpp
index 28a6a1ce7..8620c7eaf 100644
--- a/src/slic3r/GUI/GLModel.cpp
+++ b/src/slic3r/GUI/GLModel.cpp
@@ -8,15 +8,56 @@
 #include "libslic3r/TriangleMesh.hpp"
 #include "libslic3r/Model.hpp"
 #include "libslic3r/Polygon.hpp"
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+#include "libslic3r/BuildVolume.hpp"
+#include "libslic3r/Geometry/ConvexHull.hpp"
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
 
 #include <boost/filesystem/operations.hpp>
 #include <boost/algorithm/string/predicate.hpp>
 
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+#if ENABLE_SMOOTH_NORMALS
+#include <igl/per_face_normals.h>
+#include <igl/per_corner_normals.h>
+#include <igl/per_vertex_normals.h>
+#endif // ENABLE_SMOOTH_NORMALS
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+
 #include <GL/glew.h>
 
 namespace Slic3r {
 namespace GUI {
 
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+#if ENABLE_SMOOTH_NORMALS
+static void smooth_normals_corner(const TriangleMesh& mesh, std::vector<stl_normal>& normals)
+{
+    using MapMatrixXfUnaligned = Eigen::Map<const Eigen::Matrix<float, Eigen::Dynamic, Eigen::Dynamic, Eigen::RowMajor | Eigen::DontAlign>>;
+    using MapMatrixXiUnaligned = Eigen::Map<const Eigen::Matrix<int, Eigen::Dynamic, Eigen::Dynamic, Eigen::RowMajor | Eigen::DontAlign>>;
+
+    std::vector<Vec3f> face_normals = its_face_normals(mesh.its);
+
+    Eigen::MatrixXd vertices = MapMatrixXfUnaligned(mesh.its.vertices.front().data(),
+        Eigen::Index(mesh.its.vertices.size()), 3).cast<double>();
+    Eigen::MatrixXi indices = MapMatrixXiUnaligned(mesh.its.indices.front().data(),
+        Eigen::Index(mesh.its.indices.size()), 3);
+    Eigen::MatrixXd in_normals = MapMatrixXfUnaligned(face_normals.front().data(),
+        Eigen::Index(face_normals.size()), 3).cast<double>();
+    Eigen::MatrixXd out_normals;
+
+    igl::per_corner_normals(vertices, indices, in_normals, 1.0, out_normals);
+
+    normals = std::vector<stl_normal>(mesh.its.vertices.size());
+    for (size_t i = 0; i < mesh.its.indices.size(); ++i) {
+        for (size_t j = 0; j < 3; ++j) {
+            normals[mesh.its.indices[i][j]] = out_normals.row(i * 3 + j).cast<float>();
+        }
+    }
+}
+#endif // ENABLE_SMOOTH_NORMALS
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+
 #if ENABLE_GLBEGIN_GLEND_REMOVAL
 void GLModel::Geometry::reserve_vertices(size_t vertices_count)
 {
@@ -207,6 +248,37 @@ Vec2f GLModel::Geometry::extract_tex_coord_2(size_t id) const
     return { *(start + 0), *(start + 1) };
 }
 
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+void GLModel::Geometry::set_vertex(size_t id, const Vec3f& position, const Vec3f& normal)
+{
+    assert(format.vertex_layout == EVertexLayout::P3N3);
+    assert(id < vertices_count());
+    if (id < vertices_count()) {
+        float* start = &vertices[id * vertex_stride_floats(format)];
+        *(start + 0) = position.x();
+        *(start + 1) = position.y();
+        *(start + 2) = position.z();
+        *(start + 3) = normal.x();
+        *(start + 4) = normal.y();
+        *(start + 5) = normal.z();
+    }
+}
+
+void GLModel::Geometry::set_ushort_index(size_t id, unsigned short index)
+{
+    assert(id < indices_count());
+    if (id < indices_count())
+        ::memcpy(indices.data() + id * sizeof(unsigned short), &index, sizeof(unsigned short));
+}
+
+void GLModel::Geometry::set_uint_index(size_t id, unsigned int index)
+{
+    assert(id < indices_count());
+    if (id < indices_count())
+        ::memcpy(indices.data() + id * sizeof(unsigned int), &index, sizeof(unsigned int));
+}
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+
 unsigned int GLModel::Geometry::extract_uint_index(size_t id) const
 {
     if (format.index_type != EIndexType::UINT) {
@@ -219,7 +291,7 @@ unsigned int GLModel::Geometry::extract_uint_index(size_t id) const
         return -1;
     }
 
-    unsigned int ret = -1;
+    unsigned int ret = (unsigned int)-1;
     ::memcpy(&ret, indices.data() + id * index_stride_bytes(format), sizeof(unsigned int));
     return ret;
 }
@@ -236,11 +308,23 @@ unsigned short GLModel::Geometry::extract_ushort_index(size_t id) const
         return -1;
     }
 
-    unsigned short ret = -1;
+    unsigned short ret = (unsigned short)-1;
     ::memcpy(&ret, indices.data() + id * index_stride_bytes(format), sizeof(unsigned short));
     return ret;
 }
 
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+void GLModel::Geometry::remove_vertex(size_t id)
+{
+    assert(id < vertices_count());
+    if (id < vertices_count()) {
+        size_t stride = vertex_stride_floats(format);
+        std::vector<float>::iterator it = vertices.begin() + id * stride;
+        vertices.erase(it, it + stride);
+    }
+}
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+
 size_t GLModel::Geometry::vertex_stride_floats(const Format& format)
 {
     switch (format.vertex_layout)
@@ -461,10 +545,58 @@ void GLModel::init_from(const Geometry& data)
 }
 
 #if ENABLE_GLBEGIN_GLEND_REMOVAL
+#if ENABLE_SMOOTH_NORMALS
+void GLModel::init_from(const TriangleMesh& mesh, bool smooth_normals)
+{
+    if (smooth_normals) {
+        if (is_initialized()) {
+            // call reset() if you want to reuse this model
+            assert(false);
+            return;
+        }
+
+        if (mesh.its.vertices.empty() || mesh.its.indices.empty()) {
+            assert(false);
+            return;
+        }
+
+        std::vector<stl_normal> normals;
+        smooth_normals_corner(mesh, normals);
+
+        const indexed_triangle_set& its = mesh.its;
+        Geometry& data = m_render_data.geometry;
+        data.format = { Geometry::EPrimitiveType::Triangles, Geometry::EVertexLayout::P3N3, GLModel::Geometry::index_type(3 * its.indices.size()) };
+        data.reserve_vertices(3 * its.indices.size());
+        data.reserve_indices(3 * its.indices.size());
+
+        // vertices
+        for (size_t i = 0; i < its.vertices.size(); ++i) {
+            data.add_vertex(its.vertices[i], normals[i]);
+        }
+
+        // indices
+        for (size_t i = 0; i < its.indices.size(); ++i) {
+            const stl_triangle_vertex_indices& idx = its.indices[i];
+            if (data.format.index_type == GLModel::Geometry::EIndexType::USHORT)
+                data.add_ushort_triangle((unsigned short)idx(0), (unsigned short)idx(1), (unsigned short)idx(2));
+            else
+                data.add_uint_triangle((unsigned int)idx(0), (unsigned int)idx(1), (unsigned int)idx(2));
+        }
+
+        // update bounding box
+        for (size_t i = 0; i < vertices_count(); ++i) {
+            m_bounding_box.merge(m_render_data.geometry.extract_position_3(i).cast<double>());
+        }
+    }
+    else
+        init_from(mesh.its);
+}
+#else
 void GLModel::init_from(const TriangleMesh& mesh)
 {
     init_from(mesh.its);
 }
+#endif // ENABLE_SMOOTH_NORMALS
 
 void GLModel::init_from(const indexed_triangle_set& its)
 #else
@@ -484,21 +616,24 @@ void GLModel::init_from(const indexed_triangle_set& its, const BoundingBoxf3 &bb
     }
 
     Geometry& data = m_render_data.geometry;
-    data.format = { Geometry::EPrimitiveType::Triangles, Geometry::EVertexLayout::P3N3, Geometry::EIndexType::UINT };
+    data.format = { Geometry::EPrimitiveType::Triangles, Geometry::EVertexLayout::P3N3, GLModel::Geometry::index_type(3 * its.indices.size()) };
     data.reserve_vertices(3 * its.indices.size());
     data.reserve_indices(3 * its.indices.size());
 
     // vertices + indices
     unsigned int vertices_counter = 0;
     for (uint32_t i = 0; i < its.indices.size(); ++i) {
-        stl_triangle_vertex_indices face = its.indices[i];
-        stl_vertex                  vertex[3] = { its.vertices[face[0]], its.vertices[face[1]], its.vertices[face[2]] };
-        stl_vertex                  n = face_normal_normalized(vertex);
+        const stl_triangle_vertex_indices face = its.indices[i];
+        const stl_vertex                  vertex[3] = { its.vertices[face[0]], its.vertices[face[1]], its.vertices[face[2]] };
+        const stl_vertex                  n = face_normal_normalized(vertex);
         for (size_t j = 0; j < 3; ++j) {
             data.add_vertex(vertex[j], n);
         }
         vertices_counter += 3;
-        data.add_uint_triangle(vertices_counter - 3, vertices_counter - 2, vertices_counter - 1);
+        if (data.format.index_type == GLModel::Geometry::EIndexType::USHORT)
+            data.add_ushort_triangle((unsigned short)vertices_counter - 3, (unsigned short)vertices_counter - 2, (unsigned short)vertices_counter - 1);
+        else
+            data.add_uint_triangle(vertices_counter - 3, vertices_counter - 2, vertices_counter - 1);
     }
 
     // update bounding box
@@ -721,6 +856,9 @@ void GLModel::render()
 void GLModel::render() const
 #endif // ENABLE_GLBEGIN_GLEND_REMOVAL
 {
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+    render(std::make_pair<size_t, size_t>(0, indices_count()));
+#else
     GLShaderProgram* shader = wxGetApp().get_current_shader();
 
 #if ENABLE_GLBEGIN_GLEND_REMOVAL
@@ -809,8 +947,71 @@ void GLModel::render() const
         glsafe(::glBindBuffer(GL_ARRAY_BUFFER, 0));
     }
 #endif // ENABLE_GLBEGIN_GLEND_REMOVAL
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
 }
 
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+void GLModel::render(const std::pair<size_t, size_t>& range)
+{
+    if (m_render_disabled)
+        return;
+
+    if (range.second == range.first)
+        return;
+
+    GLShaderProgram* shader = wxGetApp().get_current_shader();
+
+    if (shader == nullptr)
+        return;
+
+    // sends data to gpu if not done yet
+    if (m_render_data.vbo_id == 0 || m_render_data.ibo_id == 0) {
+        if (m_render_data.geometry.vertices_count() > 0 && m_render_data.geometry.indices_count() > 0 && !send_to_gpu())
+            return;
+    }
+
+    const Geometry& data = m_render_data.geometry;
+
+    const GLenum mode = get_primitive_mode(data.format);
+    const GLenum index_type = get_index_type(data.format);
+
+    const size_t vertex_stride_bytes = Geometry::vertex_stride_bytes(data.format);
+    const bool position = Geometry::has_position(data.format);
+    const bool normal = Geometry::has_normal(data.format);
+    const bool tex_coord = Geometry::has_tex_coord(data.format);
+
+    glsafe(::glBindBuffer(GL_ARRAY_BUFFER, m_render_data.vbo_id));
+
+    if (position) {
+        glsafe(::glVertexPointer(Geometry::position_stride_floats(data.format), GL_FLOAT, vertex_stride_bytes, (const void*)Geometry::position_offset_bytes(data.format)));
+        glsafe(::glEnableClientState(GL_VERTEX_ARRAY));
+    }
+    if (normal) {
+        glsafe(::glNormalPointer(GL_FLOAT, vertex_stride_bytes, (const void*)Geometry::normal_offset_bytes(data.format)));
+        glsafe(::glEnableClientState(GL_NORMAL_ARRAY));
+    }
+    if (tex_coord) {
+        glsafe(::glTexCoordPointer(Geometry::tex_coord_stride_floats(data.format), GL_FLOAT, vertex_stride_bytes, (const void*)Geometry::tex_coord_offset_bytes(data.format)));
+        glsafe(::glEnableClientState(GL_TEXTURE_COORD_ARRAY));
+    }
+
+    shader->set_uniform("uniform_color", data.color);
+
+    glsafe(::glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, m_render_data.ibo_id));
+    glsafe(::glDrawElements(mode, range.second - range.first + 1, index_type, (const void*)(range.first * Geometry::index_stride_bytes(data.format))));
+    glsafe(::glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0));
+
+    if (tex_coord)
+        glsafe(::glDisableClientState(GL_TEXTURE_COORD_ARRAY));
+    if (normal)
+        glsafe(::glDisableClientState(GL_NORMAL_ARRAY));
+    if (position)
+        glsafe(::glDisableClientState(GL_VERTEX_ARRAY));
+
+    glsafe(::glBindBuffer(GL_ARRAY_BUFFER, 0));
+}
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+
 #if ENABLE_GLBEGIN_GLEND_REMOVAL
 void GLModel::render_instanced(unsigned int instances_vbo, unsigned int instances_count)
 #else
@@ -1027,6 +1228,62 @@ static void append_triangle(GLModel::Geometry& data, unsigned short v1, unsigned
 }
 #endif // ENABLE_GLBEGIN_GLEND_REMOVAL
 
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+template<typename Fn>
+inline bool all_vertices_inside(const GLModel::Geometry& geometry, Fn fn)
+{
+    const size_t position_stride_floats = geometry.position_stride_floats(geometry.format);
+    const size_t position_offset_floats = geometry.position_offset_floats(geometry.format);
+    assert(position_stride_floats == 3);
+    if (geometry.vertices.empty() || position_stride_floats != 3)
+        return false;
+
+    for (auto it = geometry.vertices.begin(); it != geometry.vertices.end(); ) {
+        it += position_offset_floats;
+        if (!fn({ *it, *(it + 1), *(it + 2) }))
+            return false;
+        it += (geometry.vertex_stride_floats(geometry.format) - position_offset_floats - position_stride_floats);
+    }
+    return true;
+}
+
+bool contains(const BuildVolume& volume, const GLModel& model, bool ignore_bottom)
+{
+    static constexpr const double epsilon = BuildVolume::BedEpsilon;
+    switch (volume.type()) {
+    case BuildVolume::Type::Rectangle:
+    {
+        BoundingBox3Base<Vec3d> build_volume = volume.bounding_volume().inflated(epsilon);
+        if (volume.max_print_height() == 0.0)
+            build_volume.max.z() = std::numeric_limits<double>::max();
+        if (ignore_bottom)
+            build_volume.min.z() = -std::numeric_limits<double>::max();
+        const BoundingBoxf3& model_box = model.get_bounding_box();
+        return build_volume.contains(model_box.min) && build_volume.contains(model_box.max);
+    }
+    case BuildVolume::Type::Circle:
+    {
+        const Geometry::Circled& circle = volume.circle();
+        const Vec2f c = unscaled<float>(circle.center);
+        const float r = unscaled<double>(circle.radius) + float(epsilon);
+        const float r2 = sqr(r);
+        return volume.max_print_height() == 0.0 ?
+            all_vertices_inside(model.get_geometry(), [c, r2](const Vec3f& p) { return (to_2d(p) - c).squaredNorm() <= r2; }) :
+
+            all_vertices_inside(model.get_geometry(), [c, r2, z = volume.max_print_height() + epsilon](const Vec3f& p) { return (to_2d(p) - c).squaredNorm() <= r2 && p.z() <= z; });
+    }
+    case BuildVolume::Type::Convex:
+        //FIXME doing test on convex hull until we learn to do test on non-convex polygons efficiently.
+    case BuildVolume::Type::Custom:
+        return volume.max_print_height() == 0.0 ?
+            all_vertices_inside(model.get_geometry(), [&volume](const Vec3f& p) { return Geometry::inside_convex_polygon(volume.top_bottom_convex_hull_decomposition_bed(), to_2d(p).cast<double>()); }) :
+            all_vertices_inside(model.get_geometry(), [&volume, z = volume.max_print_height() + epsilon](const Vec3f& p) { return Geometry::inside_convex_polygon(volume.top_bottom_convex_hull_decomposition_bed(), to_2d(p).cast<double>()) && p.z() <= z; });
+    default:
+        return true;
+    }
+}
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+
 GLModel::Geometry stilized_arrow(unsigned short resolution, float tip_radius, float tip_height, float stem_radius, float stem_height)
 {
 #if !ENABLE_GLBEGIN_GLEND_REMOVAL
diff --git a/src/slic3r/GUI/GLModel.hpp b/src/slic3r/GUI/GLModel.hpp
index 72c50ee11..3b268dab7 100644
--- a/src/slic3r/GUI/GLModel.hpp
+++ b/src/slic3r/GUI/GLModel.hpp
@@ -14,6 +14,9 @@ namespace Slic3r {
 class TriangleMesh;
 class Polygon;
 using Polygons = std::vector<Polygon>;
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+class BuildVolume;
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
 
 namespace GUI {
 
@@ -89,6 +92,13 @@ namespace GUI {
             void add_vertex(const Vec3f& position, const Vec2f& tex_coord);  // EVertexLayout::P3T2
             void add_vertex(const Vec3f& position, const Vec3f& normal);     // EVertexLayout::P3N3
 
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+            void set_vertex(size_t id, const Vec3f& position, const Vec3f& normal); // EVertexLayout::P3N3
+
+            void set_ushort_index(size_t id, unsigned short index);
+            void set_uint_index(size_t id, unsigned int index);
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+
             void add_ushort_index(unsigned short id);
             void add_uint_index(unsigned int id);
 
@@ -106,7 +116,11 @@ namespace GUI {
             unsigned int extract_uint_index(size_t id) const;
             unsigned short extract_ushort_index(size_t id) const;
 
-            bool is_empty() const { return vertices.empty() || indices.empty(); }
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+            void remove_vertex(size_t id);
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+
+            bool is_empty() const { return vertices_count() == 0 || indices_count() == 0; }
 
             size_t vertices_count() const { return vertices.size() / vertex_stride_floats(format); }
             size_t indices_count() const  { return indices.size() / index_stride_bytes(format); }
@@ -179,6 +193,16 @@ namespace GUI {
         std::vector<RenderData> m_render_data;
 #endif // ENABLE_GLBEGIN_GLEND_REMOVAL
 
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+        // By default the vertex and index buffers data are sent to gpu at the first call to render() method.
+        // If you need to initialize a model from outside the main thread, so that a call to render() may happen
+        // before the initialization is complete, use the methods:
+        // disable_render()
+        // ... do your initialization ...
+        // enable_render()
+        // to keep the data on cpu side until needed.
+        bool m_render_disabled{ false };
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
         BoundingBoxf3 m_bounding_box;
         std::string m_filename;
 
@@ -197,8 +221,16 @@ namespace GUI {
 
         size_t indices_size_bytes() const { return indices_count() * Geometry::index_stride_bytes(m_render_data.geometry.format); }
 
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+        const Geometry& get_geometry() const { return m_render_data.geometry; }
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+
         void init_from(Geometry&& data);
+#if ENABLE_SMOOTH_NORMALS
+        void init_from(const TriangleMesh& mesh, bool smooth_normals = false);
+#else
         void init_from(const TriangleMesh& mesh);
+#endif // ENABLE_SMOOTH_NORMALS
 #else
         void init_from(const Geometry& data);
         void init_from(const indexed_triangle_set& its, const BoundingBoxf3& bbox);
@@ -219,9 +251,15 @@ namespace GUI {
         void reset();
 #if ENABLE_GLBEGIN_GLEND_REMOVAL
         void render();
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+        void render(const std::pair<size_t, size_t>& range);
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
         void render_instanced(unsigned int instances_vbo, unsigned int instances_count);
 
         bool is_initialized() const { return vertices_count() > 0 && indices_count() > 0; }
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+        bool is_empty() const { return m_render_data.geometry.is_empty(); }
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
 #else
         void render() const;
         void render_instanced(unsigned int instances_vbo, unsigned int instances_count) const;
@@ -232,6 +270,29 @@ namespace GUI {
         const BoundingBoxf3& get_bounding_box() const { return m_bounding_box; }
         const std::string& get_filename() const { return m_filename; }
 
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+        bool is_render_disabled() const { return m_render_disabled; }
+        void enable_render() { m_render_disabled = false; }
+        void disable_render() { m_render_disabled = true; }
+
+        size_t cpu_memory_used() const {
+            size_t ret = 0;
+            if (!m_render_data.geometry.vertices.empty())
+                ret += vertices_size_bytes();
+            if (!m_render_data.geometry.indices.empty())
+                ret += indices_size_bytes();
+            return ret;
+        }
+        size_t gpu_memory_used() const {
+            size_t ret = 0;
+            if (m_render_data.geometry.vertices.empty())
+                ret += vertices_size_bytes();
+            if (m_render_data.geometry.indices.empty())
+                ret += indices_size_bytes();
+            return ret;
+        }
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+
     private:
 #if ENABLE_GLBEGIN_GLEND_REMOVAL
         bool send_to_gpu();
@@ -240,6 +301,10 @@ namespace GUI {
 #endif // ENABLE_GLBEGIN_GLEND_REMOVAL
     };
 
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+    bool contains(const BuildVolume& volume, const GLModel& model, bool ignore_bottom = true);
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+
     // create an arrow with cylindrical stem and conical tip, with the given dimensions and resolution
     // the origin of the arrow is in the center of the stem cap
     // the arrow has its axis of symmetry along the Z axis and is pointing upward
diff --git a/src/slic3r/GUI/GLSelectionRectangle.cpp b/src/slic3r/GUI/GLSelectionRectangle.cpp
index 515da6de3..8cf3247cb 100644
--- a/src/slic3r/GUI/GLSelectionRectangle.cpp
+++ b/src/slic3r/GUI/GLSelectionRectangle.cpp
@@ -98,7 +98,7 @@ namespace GUI {
         color[1] = (m_state == Select) ? 1.0f : 0.3f;
         color[2] = 0.3f;
         glsafe(::glColor3fv(color));
-#endif // ENABLE_GLBEGIN_GLEND_REMOVAL
+#endif // !ENABLE_GLBEGIN_GLEND_REMOVAL
 
         glsafe(::glDisable(GL_DEPTH_TEST));
 
diff --git a/src/slic3r/GUI/GalleryDialog.cpp b/src/slic3r/GUI/GalleryDialog.cpp
index 1191e5c2e..0bc741c96 100644
--- a/src/slic3r/GUI/GalleryDialog.cpp
+++ b/src/slic3r/GUI/GalleryDialog.cpp
@@ -274,9 +274,13 @@ static void generate_thumbnail_from_model(const std::string& filename)
 
     GLVolumeCollection volumes;
     volumes.volumes.push_back(new GLVolume());
-    GLVolume* volume = volumes.volumes[0];
+    GLVolume* volume = volumes.volumes.back();
+#if ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
+    volume->model.init_from(model.mesh());
+#else
     volume->indexed_vertex_array.load_mesh(model.mesh());
     volume->indexed_vertex_array.finalize_geometry(true);
+#endif // ENABLE_GLINDEXEDVERTEXARRAY_REMOVAL
     volume->set_instance_transformation(model.objects[0]->instances[0]->get_transformation());
     volume->set_volume_transformation(model.objects[0]->volumes[0]->get_transformation());
 
diff --git a/src/slic3r/GUI/ImGuiWrapper.cpp b/src/slic3r/GUI/ImGuiWrapper.cpp
index e70c1111b..4b75befb6 100644
--- a/src/slic3r/GUI/ImGuiWrapper.cpp
+++ b/src/slic3r/GUI/ImGuiWrapper.cpp
@@ -1444,8 +1444,8 @@ void ImGuiWrapper::render_draw_data(ImDrawData *draw_data)
 {
     // Avoid rendering when minimized, scale coordinates for retina displays (screen coordinates != framebuffer coordinates)
     ImGuiIO& io = ImGui::GetIO();
-    int fb_width = (int)(draw_data->DisplaySize.x * io.DisplayFramebufferScale.x);
-    int fb_height = (int)(draw_data->DisplaySize.y * io.DisplayFramebufferScale.y);
+    const int fb_width = (int)(draw_data->DisplaySize.x * io.DisplayFramebufferScale.x);
+    const int fb_height = (int)(draw_data->DisplaySize.y * io.DisplayFramebufferScale.y);
     if (fb_width == 0 || fb_height == 0)
         return;
     draw_data->ScaleClipRects(io.DisplayFramebufferScale);
@@ -1488,8 +1488,7 @@ void ImGuiWrapper::render_draw_data(ImDrawData *draw_data)
 
     // Render command lists
     ImVec2 pos = draw_data->DisplayPos;
-    for (int n = 0; n < draw_data->CmdListsCount; n++)
-    {
+    for (int n = 0; n < draw_data->CmdListsCount; ++n) {
         const ImDrawList* cmd_list = draw_data->CmdLists[n];
         const ImDrawVert* vtx_buffer = cmd_list->VtxBuffer.Data;
         const ImDrawIdx* idx_buffer = cmd_list->IdxBuffer.Data;
@@ -1497,19 +1496,14 @@ void ImGuiWrapper::render_draw_data(ImDrawData *draw_data)
         glsafe(::glTexCoordPointer(2, GL_FLOAT, sizeof(ImDrawVert), (const GLvoid*)((const char*)vtx_buffer + IM_OFFSETOF(ImDrawVert, uv))));
         glsafe(::glColorPointer(4, GL_UNSIGNED_BYTE, sizeof(ImDrawVert), (const GLvoid*)((const char*)vtx_buffer + IM_OFFSETOF(ImDrawVert, col))));
 
-        for (int cmd_i = 0; cmd_i < cmd_list->CmdBuffer.Size; cmd_i++)
-        {
+        for (int cmd_i = 0; cmd_i < cmd_list->CmdBuffer.Size; ++cmd_i) {
             const ImDrawCmd* pcmd = &cmd_list->CmdBuffer[cmd_i];
             if (pcmd->UserCallback)
-            {
                 // User callback (registered via ImDrawList::AddCallback)
                 pcmd->UserCallback(cmd_list, pcmd);
-            }
-            else
-            {
+            else {
                 ImVec4 clip_rect = ImVec4(pcmd->ClipRect.x - pos.x, pcmd->ClipRect.y - pos.y, pcmd->ClipRect.z - pos.x, pcmd->ClipRect.w - pos.y);
-                if (clip_rect.x < fb_width && clip_rect.y < fb_height && clip_rect.z >= 0.0f && clip_rect.w >= 0.0f)
-                {
+                if (clip_rect.x < fb_width && clip_rect.y < fb_height && clip_rect.z >= 0.0f && clip_rect.w >= 0.0f) {
                     // Apply scissor/clipping rectangle
                     glsafe(::glScissor((int)clip_rect.x, (int)(fb_height - clip_rect.w), (int)(clip_rect.z - clip_rect.x), (int)(clip_rect.w - clip_rect.y)));