diff --git a/xs/CMakeLists.txt b/xs/CMakeLists.txt
index 2f8eb14c5..9e23112c5 100644
--- a/xs/CMakeLists.txt
+++ b/xs/CMakeLists.txt
@@ -349,8 +349,8 @@ if(APPLE)
     target_link_libraries(XS "-undefined dynamic_lookup")
 endif()
 target_link_libraries(XS libslic3r libslic3r_gui admesh clipper nowide polypartition poly2tri)
-if(SLIC3R_DEBUG)
-    target_link_libraries(Shiny)
+if(SLIC3R_PROFILE)
+    target_link_libraries(XS Shiny)
 endif()
 
 # Add the OpenGL and GLU libraries.
@@ -393,7 +393,7 @@ endif ()
 
 if (SLIC3R_PROFILE)
     message("Slic3r will be built with a Shiny invasive profiler")
-    target_compile_definitions(XS PRIVATE -DSLIC3R_PROFILE)
+    add_definitions(-DSLIC3R_PROFILE)
 endif ()
 
 if (SLIC3R_HAS_BROKEN_CROAK)
@@ -552,7 +552,7 @@ endif()
 add_executable(slic3r ${PROJECT_SOURCE_DIR}/src/slic3r.cpp)
 target_include_directories(XS PRIVATE src src/libslic3r)
 target_link_libraries(slic3r libslic3r libslic3r_gui admesh ${Boost_LIBRARIES} clipper ${EXPAT_LIBRARIES} ${GLEW_LIBRARIES} polypartition poly2tri ${TBB_LIBRARIES} ${wxWidgets_LIBRARIES})
-if(SLIC3R_DEBUG)
+if(SLIC3R_PROFILE)
     target_link_libraries(Shiny)
 endif()
 if (APPLE)
diff --git a/xs/src/Shiny/ShinyManager.c b/xs/src/Shiny/ShinyManager.c
index 2cb0df4c2..6b2811851 100644
--- a/xs/src/Shiny/ShinyManager.c
+++ b/xs/src/Shiny/ShinyManager.c
@@ -90,8 +90,8 @@ ShinyNode* _ShinyManager_dummyNodeTable[] = { NULL };
 
 /* primary hash function */
 SHINY_INLINE uint32_t hash_value(void* a_pParent, void* a_pZone) {
-//	uint32_t a = (uint32_t) a_pParent + (uint32_t) a_pZone;
-	uint32_t a = *reinterpret_cast<uint32_t*>(&a_pParent) + *reinterpret_cast<uint32_t*>(&a_pZone);
+	uint32_t a = (uint32_t) a_pParent + (uint32_t) a_pZone;
+//	uint32_t a = *reinterpret_cast<uint32_t*>(&a_pParent) + *reinterpret_cast<uint32_t*>(&a_pZone);
 
 	a = (a+0x7ed55d16) + (a<<12);
 	a = (a^0xc761c23c) ^ (a>>19);
diff --git a/xs/src/libslic3r/GCode.cpp b/xs/src/libslic3r/GCode.cpp
index 47bd6bc07..f713015f7 100644
--- a/xs/src/libslic3r/GCode.cpp
+++ b/xs/src/libslic3r/GCode.cpp
@@ -20,6 +20,8 @@
 
 #include "SVG.hpp"
 
+#include <Shiny/Shiny.h>
+
 #if 0
 // Enable debugging and asserts, even in the release build.
 #define DEBUG
@@ -348,6 +350,8 @@ std::vector<std::pair<coordf_t, std::vector<GCode::LayerToPrint>>> GCode::collec
 
 void GCode::do_export(Print *print, const char *path)
 {
+    PROFILE_CLEAR();
+
     // Remove the old g-code if it exists.
     boost::nowide::remove(path);
 
@@ -384,10 +388,16 @@ void GCode::do_export(Print *print, const char *path)
         throw std::runtime_error(
             std::string("Failed to rename the output G-code file from ") + path_tmp + " to " + path + '\n' +
             "Is " + path_tmp + " locked?" + '\n');
+
+    // Write the profiler measurements to file
+    PROFILE_UPDATE();
+    PROFILE_OUTPUT(debug_out_path("gcode-export-profile.txt").c_str());
 }
 
 void GCode::_do_export(Print &print, FILE *file)
 {
+    PROFILE_FUNC();
+
     // resets time estimator
     m_time_estimator.reset();
 
@@ -1987,44 +1997,41 @@ std::string GCode::extrude_support(const ExtrusionEntityCollection &support_fill
     return gcode;
 }
 
-void GCode::_write(FILE* file, const std::string& what)
+void GCode::_write(FILE* file, const char *what, size_t size)
 {
-    if (!what.empty()) {
+    if (size > 0) {
         // writes string to file
-        fwrite(what.data(), 1, what.size(), file);
+        fwrite(what, 1, size, file);
         // updates time estimator and gcode lines vector
-        const char endLine = '\n';
-        std::string::size_type beginPos = 0;
-        std::string::size_type endPos = what.find_first_of(endLine, beginPos);
-        while (endPos != std::string::npos) {
-            std::string line = what.substr(beginPos, endPos - beginPos + 1);
-            m_time_estimator.add_gcode_line(line);
-            beginPos = endPos + 1;
-            endPos = what.find_first_of(endLine, beginPos);
-        }
+        m_time_estimator.add_gcode_block(what);
     }
 }
 
-void GCode::_writeln(FILE* file, const std::string& what)
+void GCode::_writeln(FILE* file, const std::string &what)
 {
-    if (!what.empty()) {
-        if (what.back() != '\n')
-            _write_format(file, "%s\n", what.c_str());
-        else
-            _write(file, what);
-    }
+    if (! what.empty())
+        _write(file, (what.back() == '\n') ? what : (what + '\n'));
 }
 
 void GCode::_write_format(FILE* file, const char* format, ...)
 {
-    char buffer[1024];
     va_list args;
     va_start(args, format);
-    int res = ::vsnprintf(buffer, 1024, format, args);
+    int buflen = 
+#ifdef _MSC_VER
+        _vscprintf(format, args);
+#else
+        vsnprintf(nullptr, 0, format, args);
+#endif
+    char buffer[1024];
+    bool buffer_dynamic = buflen > 1024;
+    char *bufptr = buffer_dynamic ? (char*)malloc(buflen) : buffer;
+    int res = ::vsnprintf(bufptr, buflen, format, args);
+    if (res >= 0 && bufptr[0] != 0)
+        _write(file, bufptr, buflen);
     va_end(args);
-
-    if (res >= 0)
-        _writeln(file, buffer);
+    if (buffer_dynamic)
+        free(bufptr);
 }
 
 std::string GCode::_extrude(const ExtrusionPath &path, std::string description, double speed)
diff --git a/xs/src/libslic3r/GCode.hpp b/xs/src/libslic3r/GCode.hpp
index cb8b0027a..5c622ec2d 100644
--- a/xs/src/libslic3r/GCode.hpp
+++ b/xs/src/libslic3r/GCode.hpp
@@ -278,7 +278,8 @@ protected:
     GCodeTimeEstimator m_time_estimator;
 
     // Write a string into a file.
-    void _write(FILE* file, const std::string& what);
+    void _write(FILE* file, const std::string& what) { this->_write(file, what.c_str(), what.size()); }
+    void _write(FILE* file, const char *what, size_t size);
 
     // Write a string into a file. 
     // Add a newline, if the string does not end with a newline already.
diff --git a/xs/src/libslic3r/GCode/SpiralVase.cpp b/xs/src/libslic3r/GCode/SpiralVase.cpp
index fd300067f..892d3b4cc 100644
--- a/xs/src/libslic3r/GCode/SpiralVase.cpp
+++ b/xs/src/libslic3r/GCode/SpiralVase.cpp
@@ -4,17 +4,7 @@
 
 namespace Slic3r {
 
-std::string
-_format_z(float z)
-{
-    std::ostringstream ss;
-    ss << std::fixed << std::setprecision(3)
-       << z;
-    return ss.str();
-}
-
-std::string
-SpiralVase::process_layer(const std::string &gcode)
+std::string SpiralVase::process_layer(const std::string &gcode)
 {
     /*  This post-processor relies on several assumptions:
         - all layers are processed through it, including those that are not supposed
@@ -38,16 +28,17 @@ SpiralVase::process_layer(const std::string &gcode)
     bool set_z = false;
     
     {
+        //FIXME Performance warning: This copies the GCodeConfig of the reader.
         GCodeReader r = this->_reader;  // clone
         r.parse(gcode, [&total_layer_length, &layer_height, &z, &set_z]
-            (GCodeReader &, const GCodeReader::GCodeLine &line) {
-            if (line.cmd == "G1") {
-                if (line.extruding()) {
-                    total_layer_length += line.dist_XY();
-                } else if (line.has('Z')) {
-                    layer_height += line.dist_Z();
+            (GCodeReader &reader, const GCodeReader::GCodeLine &line) {
+            if (line.cmd_is("G1")) {
+                if (line.extruding(reader)) {
+                    total_layer_length += line.dist_XY(reader);
+                } else if (line.has(Z)) {
+                    layer_height += line.dist_Z(reader);
                     if (!set_z) {
-                        z = line.new_Z();
+                        z = line.new_Z(reader);
                         set_z = true;
                     }
                 }
@@ -60,22 +51,22 @@ SpiralVase::process_layer(const std::string &gcode)
     
     std::string new_gcode;
     this->_reader.parse(gcode, [&new_gcode, &z, &layer_height, &total_layer_length]
-        (GCodeReader &, GCodeReader::GCodeLine line) {
-        if (line.cmd == "G1") {
-            if (line.has('Z')) {
+        (GCodeReader &reader, GCodeReader::GCodeLine line) {
+        if (line.cmd_is("G1")) {
+            if (line.has_z()) {
                 // If this is the initial Z move of the layer, replace it with a
                 // (redundant) move to the last Z of previous layer.
-                line.set('Z', _format_z(z));
-                new_gcode += line.raw + '\n';
+                line.set(reader, Z, z);
+                new_gcode += line.raw() + '\n';
                 return;
             } else {
-                float dist_XY = line.dist_XY();
+                float dist_XY = line.dist_XY(reader);
                 if (dist_XY > 0) {
                     // horizontal move
-                    if (line.extruding()) {
+                    if (line.extruding(reader)) {
                         z += dist_XY * layer_height / total_layer_length;
-                        line.set('Z', _format_z(z));
-                        new_gcode += line.raw + '\n';
+                        line.set(reader, Z, z);
+                        new_gcode += line.raw() + '\n';
                     }
                     return;
                 
@@ -87,7 +78,7 @@ SpiralVase::process_layer(const std::string &gcode)
                 }
             }
         }
-        new_gcode += line.raw + '\n';
+        new_gcode += line.raw() + '\n';
     });
     
     return new_gcode;
diff --git a/xs/src/libslic3r/GCode/SpiralVase.hpp b/xs/src/libslic3r/GCode/SpiralVase.hpp
index 234642524..60aa668d8 100644
--- a/xs/src/libslic3r/GCode/SpiralVase.hpp
+++ b/xs/src/libslic3r/GCode/SpiralVase.hpp
@@ -13,7 +13,7 @@ class SpiralVase {
     SpiralVase(const PrintConfig &config)
         : enable(false), _config(&config)
     {
-        this->_reader.Z = this->_config->z_offset;
+        this->_reader.z() = this->_config->z_offset;
         this->_reader.apply_config(*this->_config);
     };
     std::string process_layer(const std::string &gcode);
diff --git a/xs/src/libslic3r/GCodeReader.cpp b/xs/src/libslic3r/GCodeReader.cpp
index 453cc9f94..86009fb0f 100644
--- a/xs/src/libslic3r/GCodeReader.cpp
+++ b/xs/src/libslic3r/GCodeReader.cpp
@@ -4,6 +4,8 @@
 #include <fstream>
 #include <iostream>
 
+#include <Shiny/Shiny.h>
+
 namespace Slic3r {
 
 void GCodeReader::apply_config(const GCodeConfig &config)
@@ -26,58 +28,121 @@ void GCodeReader::parse(const std::string &gcode, callback_t callback)
         this->parse_line(line, callback);
 }
 
-void GCodeReader::parse_line(std::string line, callback_t callback)
+static inline bool is_whitespace(char c)
 {
-    GCodeLine gline(this);
-    gline.raw = line;
-    if (this->verbose)
-        std::cout << line << std::endl;
-    
-    // strip comment
-    {
-        size_t pos = line.find(';');
-        if (pos != std::string::npos) {
-            gline.comment = line.substr(pos+1);
-            line.erase(pos);
-        }
-    }
+    return c == ' ' || c == '\t';
+}
+
+static inline bool is_end_of_line(char c)
+{
+    return c == '\r' || c == '\n' || c == 0;
+}
+
+static inline bool is_end_of_gcode_line(char c)
+{
+    return c == ';' || is_end_of_line(c);
+}
+
+static inline bool is_end_of_word(char c)
+{
+    return is_whitespace(c) || is_end_of_gcode_line(c);
+}
+
+static inline const char* skip_whitespaces(const char *c)
+{
+    for (; is_whitespace(*c); ++ c);
+    return c;
+}
+
+static inline const char* skip_word(const char *c)
+{
+    for (; ! is_end_of_word(*c); ++ c);
+    return c;
+}
+
+const char* GCodeReader::parse_line_internal(const char *ptr, GCodeLine &gline, std::pair<const char*, const char*> &command)
+{
+    PROFILE_FUNC();
     
     // command and args
+    const char *c = ptr;
     {
-        std::vector<std::string> args;
-        boost::split(args, line, boost::is_any_of(" "));
-        
-        // first one is cmd
-        gline.cmd = args.front();
-        args.erase(args.begin());
-        
-        for (std::string &arg : args) {
-            if (arg.size() < 2) continue;
-            gline.args.insert(std::make_pair(arg[0], arg.substr(1)));
+        PROFILE_BLOCK(command_and_args);
+        // Skip the whitespaces.
+        command.first = skip_whitespaces(c);
+        // Skip the command.
+        c = command.second = skip_word(command.first);
+        // Up to the end of line or comment.
+		while (! is_end_of_gcode_line(*c)) {
+            // Skip whitespaces.
+            c = skip_whitespaces(c);
+			if (is_end_of_gcode_line(*c))
+				break;
+            // Check the name of the axis.
+            Axis axis = NUM_AXES;
+            switch (*c) {
+            case 'X': axis = X; break;
+            case 'Y': axis = Y; break;
+            case 'Z': axis = Z; break;
+            case 'F': axis = F; break;
+            default:
+                if (*c == m_extrusion_axis)
+                    axis = E;
+                break;
+            }
+            if (axis != NUM_AXES) {
+                // Try to parse the numeric value.
+                char   *pend = nullptr;
+                double  v = strtod(++ c, &pend);
+                if (pend != nullptr && is_end_of_word(*pend)) {
+                    // The axis value has been parsed correctly.
+                    gline.m_axis[int(axis)] = float(v);
+                    gline.m_mask |= 1 << int(axis);
+                    c = pend;
+                } else
+                    // Skip the rest of the word.
+                    c = skip_word(c);
+            } else
+                // Skip the rest of the word.
+                c = skip_word(c);
         }
     }
     
-    // convert extrusion axis
-    if (m_extrusion_axis != 'E') {
-        const auto it = gline.args.find(m_extrusion_axis);
-        if (it != gline.args.end()) {
-            std::swap(gline.args['E'], it->second);
-            gline.args.erase(it);
-        }
+    if (gline.has(E) && m_config.use_relative_e_distances)
+        m_position[E] = 0;
+
+    // Skip the rest of the line.
+    for (; ! is_end_of_line(*c); ++ c);
+
+    // Copy the raw string including the comment, without the trailing newlines.
+    if (c > ptr) {
+        PROFILE_BLOCK(copy_raw_string);
+        gline.m_raw.assign(ptr, c);
     }
-    
-    if (gline.has('E') && m_config.use_relative_e_distances)
-        this->E = 0;
-    
-    if (callback) callback(*this, gline);
-    
-    // update coordinates
-    if (gline.cmd == "G0" || gline.cmd == "G1" || gline.cmd == "G92") {
-        this->X = gline.new_X();
-        this->Y = gline.new_Y();
-        this->Z = gline.new_Z();
-        this->E = gline.new_E();
-        this->F = gline.new_F();
+
+    // Skip the trailing newlines.
+	if (*c == '\r')
+		++ c;
+	if (*c == '\n')
+		++ c;
+
+    if (m_verbose)
+        std::cout << gline.m_raw << std::endl;
+
+    return c;
+}
+
+void GCodeReader::update_coordinates(GCodeLine &gline, std::pair<const char*, const char*> &command)
+{
+    PROFILE_FUNC();
+    if (*command.first == 'G') {
+        int cmd_len = int(command.second - command.first);
+        if ((cmd_len == 2 && (command.first[1] == '0' || command.first[1] == '1')) ||
+            (cmd_len == 3 &&  command.first[1] == '9' && command.first[2] == '2')) {
+            for (size_t i = 0; i < NUM_AXES; ++ i)
+                if (gline.has(Axis(i)))
+                    this->m_position[i] = gline.value(Axis(i));
+        }
     }
 }
 
@@ -89,22 +154,64 @@ void GCodeReader::parse_file(const std::string &file, callback_t callback)
         this->parse_line(line, callback);
 }
 
-void GCodeReader::GCodeLine::set(char arg, std::string value)
+bool GCodeReader::GCodeLine::has_value(char axis, float &value) const
 {
-    const std::string space(" ");
-    if (this->has(arg)) {
-        size_t pos = this->raw.find(space + arg)+2;
-        size_t end = this->raw.find(' ', pos+1);
-        this->raw = this->raw.replace(pos, end-pos, value);
-    } else {
-        size_t pos = this->raw.find(' ');
-        if (pos == std::string::npos) {
-            this->raw += space + arg + value;
-        } else {
-            this->raw = this->raw.replace(pos, 0, space + arg + value);
+    const char *c = m_raw.c_str();
+    // Skip the whitespaces.
+    c = skip_whitespaces(c);
+    // Skip the command.
+    c = skip_word(c);
+    // Up to the end of line or comment.
+    while (! is_end_of_gcode_line(*c)) {
+        // Skip whitespaces.
+        c = skip_whitespaces(c);
+        if (is_end_of_gcode_line(*c))
+            break;
+        // Check the name of the axis.
+        if (*c == axis) {
+            // Try to parse the numeric value.
+            char   *pend = nullptr;
+            double  v = strtod(++ c, &pend);
+            if (pend != nullptr && is_end_of_word(*pend)) {
+                // The axis value has been parsed correctly.
+                value = float(v);
+                return true;
+            }
         }
+        // Skip the rest of the word.
+        c = skip_word(c);
     }
-    this->args[arg] = value;
+    return false;
+}
+
+void GCodeReader::GCodeLine::set(const GCodeReader &reader, const Axis axis, const float new_value, const int decimal_digits)
+{
+    std::ostringstream ss;
+    ss << std::fixed << std::setprecision(decimal_digits) << new_value;
+
+    char match[3] = " X";
+    if (int(axis) < 3)
+        match[1] += int(axis);
+    else if (axis == F)
+        match[1] = 'F';
+    else {
+        assert(axis == E);
+        match[1] = reader.extrusion_axis();
+    }
+
+    if (this->has(axis)) {
+        size_t pos = m_raw.find(match)+2;
+        size_t end = m_raw.find(' ', pos+1);
+        m_raw = m_raw.replace(pos, end-pos, ss.str());
+    } else {
+        size_t pos = m_raw.find(' ');
+        if (pos == std::string::npos)
+            m_raw += std::string(match) + ss.str();
+        else
+            m_raw = m_raw.replace(pos, 0, std::string(match) + ss.str());
+    }
+    m_axis[axis] = new_value;
+    m_mask |= 1 << int(axis);
 }
 
 }
diff --git a/xs/src/libslic3r/GCodeReader.hpp b/xs/src/libslic3r/GCodeReader.hpp
index 1792d6cde..4a7825520 100644
--- a/xs/src/libslic3r/GCodeReader.hpp
+++ b/xs/src/libslic3r/GCodeReader.hpp
@@ -11,54 +11,104 @@
 namespace Slic3r {
 
 class GCodeReader {
-public:    
+public:
     class GCodeLine {
     public:
-        GCodeReader* reader;
-        std::string raw;
-        std::string cmd;
-        std::string comment;
-        std::map<char,std::string> args;
-        
-        GCodeLine(GCodeReader* _reader) : reader(_reader) {};
-        
-        bool  has(char arg) const { return this->args.count(arg) > 0; };
-        float get_float(char arg) const { return float(atof(this->args.at(arg).c_str())); };
-        float new_X() const { return this->has('X') ? float(atof(this->args.at('X').c_str())) : this->reader->X; };
-        float new_Y() const { return this->has('Y') ? float(atof(this->args.at('Y').c_str())) : this->reader->Y; };
-        float new_Z() const { return this->has('Z') ? float(atof(this->args.at('Z').c_str())) : this->reader->Z; };
-        float new_E() const { return this->has('E') ? float(atof(this->args.at('E').c_str())) : this->reader->E; };
-        float new_F() const { return this->has('F') ? float(atof(this->args.at('F').c_str())) : this->reader->F; };
-        float dist_X() const { return this->new_X() - this->reader->X; };
-        float dist_Y() const { return this->new_Y() - this->reader->Y; };
-        float dist_Z() const { return this->new_Z() - this->reader->Z; };
-        float dist_E() const { return this->new_E() - this->reader->E; };
-        float dist_XY() const {
-            float x = this->dist_X();
-            float y = this->dist_Y();
+        GCodeLine() { reset(); }
+        void reset() { m_mask = 0; memset(m_axis, 0, sizeof(m_axis)); m_raw.clear(); }
+
+        const std::string&  raw() const { return m_raw; }
+        const std::string   cmd() const 
+            { size_t pos = m_raw.find_first_of(" \t\n;"); return (pos == std::string::npos) ? m_raw : m_raw.substr(0, pos); }
+        const std::string   comment() const
+            { size_t pos = m_raw.find(';'); return (pos == std::string::npos) ? "" : m_raw.substr(pos + 1); }
+
+        bool  has(Axis axis) const { return (m_mask & (1 << int(axis))) != 0; }
+        float value(Axis axis) const { return m_axis[axis]; }
+        bool  has_value(char axis, float &value) const;
+        float new_Z(const GCodeReader &reader) const { return this->has(Z) ? this->z() : reader.z(); }
+        float new_E(const GCodeReader &reader) const { return this->has(E) ? this->e() : reader.e(); }
+        float new_F(const GCodeReader &reader) const { return this->has(F) ? this->f() : reader.f(); }
+        float dist_X(const GCodeReader &reader) const { return this->has(X) ? (this->x() - reader.x()) : 0; }
+        float dist_Y(const GCodeReader &reader) const { return this->has(Y) ? (this->y() - reader.y()) : 0; }
+        float dist_Z(const GCodeReader &reader) const { return this->has(Z) ? (this->z() - reader.z()) : 0; }
+        float dist_E(const GCodeReader &reader) const { return this->has(E) ? (this->e() - reader.e()) : 0; }
+        float dist_XY(const GCodeReader &reader) const {
+            float x = this->has(X) ? (this->x() - reader.x()) : 0;
+            float y = this->has(Y) ? (this->y() - reader.y()) : 0;
             return sqrt(x*x + y*y);
-        };
-        bool extruding()  const { return this->cmd == "G1" && this->dist_E() > 0; };
-        bool retracting() const { return this->cmd == "G1" && this->dist_E() < 0; };
-        bool travel()     const { return this->cmd == "G1" && ! this->has('E'); };
-        void set(char arg, std::string value);
+        }
+        bool cmd_is(const char *cmd_test) const {
+            int len = strlen(cmd_test); 
+            if (strncmp(m_raw.c_str(), cmd_test, len))
+                return false;
+            char c = m_raw.c_str()[len];
+            return c == 0 || c == ' ' || c == '\t' || c == ';';
+        }
+        bool extruding(const GCodeReader &reader)  const { return this->cmd_is("G1") && this->dist_E(reader) > 0; }
+        bool retracting(const GCodeReader &reader) const { return this->cmd_is("G1") && this->dist_E(reader) < 0; }
+        bool travel()     const { return this->cmd_is("G1") && ! this->has(E); }
+        void set(const GCodeReader &reader, const Axis axis, const float new_value, const int decimal_digits = 3);
+
+        bool  has_x() const { return this->has(X); }
+        bool  has_y() const { return this->has(Y); }
+        bool  has_z() const { return this->has(Z); }
+        bool  has_e() const { return this->has(E); }
+        bool  has_f() const { return this->has(F); }
+        float x() const { return m_axis[X]; }
+        float y() const { return m_axis[Y]; }
+        float z() const { return m_axis[Z]; }
+        float e() const { return m_axis[E]; }
+        float f() const { return m_axis[F]; }
+
+    private:
+        std::string      m_raw;
+        float            m_axis[NUM_AXES];
+        uint32_t         m_mask;
+        friend class GCodeReader;
     };
+
     typedef std::function<void(GCodeReader&, const GCodeLine&)> callback_t;
     
-    float X, Y, Z, E, F;
-    bool verbose;
-    callback_t callback; 
-    
-    GCodeReader() : X(0), Y(0), Z(0), E(0), F(0), verbose(false), m_extrusion_axis('E') {};
+    GCodeReader() : m_verbose(false), m_extrusion_axis('E') { memset(m_position, 0, sizeof(m_position)); }
     void apply_config(const GCodeConfig &config);
     void apply_config(const DynamicPrintConfig &config);
     void parse(const std::string &gcode, callback_t callback);
-    void parse_line(std::string line, callback_t callback);
+    template<typename Callback>
+    const char* parse_line(const char *ptr, GCodeLine &gline, Callback &callback)
+    {
+        std::pair<const char*, const char*> cmd;
+        const char *end = parse_line_internal(ptr, gline, cmd);
+        callback(*this, gline);
+        update_coordinates(gline, cmd);
+        return end;
+    }
+    template<typename Callback>
+    void parse_line(const std::string &line, Callback &callback)
+        { GCodeLine gline; this->parse_line(line.c_str(), gline, callback); }
     void parse_file(const std::string &file, callback_t callback);
-    
+
+    float& x()       { return m_position[X]; }
+    float  x() const { return m_position[X]; }
+    float& y()       { return m_position[Y]; }
+    float  y() const { return m_position[Y]; }
+    float& z()       { return m_position[Z]; }
+    float  z() const { return m_position[Z]; }
+    float& e()       { return m_position[E]; }
+    float  e() const { return m_position[E]; }
+    float& f()       { return m_position[F]; }
+    float  f() const { return m_position[F]; }
+
+    char   extrusion_axis() const { return m_extrusion_axis; }
+
 private:
+    const char* parse_line_internal(const char *ptr, GCodeLine &gline, std::pair<const char*, const char*> &command);
+    void        update_coordinates(GCodeLine &gline, std::pair<const char*, const char*> &command);
+
     GCodeConfig m_config;
-    char m_extrusion_axis;
+    char        m_extrusion_axis;
+    float       m_position[NUM_AXES];
+    bool        m_verbose;
 };
 
 } /* namespace Slic3r */
diff --git a/xs/src/libslic3r/GCodeTimeEstimator.cpp b/xs/src/libslic3r/GCodeTimeEstimator.cpp
index 43b331676..31ee30cc1 100644
--- a/xs/src/libslic3r/GCodeTimeEstimator.cpp
+++ b/xs/src/libslic3r/GCodeTimeEstimator.cpp
@@ -4,7 +4,6 @@
 
 #include <Shiny/Shiny.h>
 
-static const std::string AXIS_STR = "XYZE";
 static const float MMMIN_TO_MMSEC = 1.0f / 60.0f;
 static const float MILLISEC_TO_SEC = 0.001f;
 static const float INCHES_TO_MM = 25.4f;
@@ -159,7 +158,9 @@ namespace Slic3r {
   {
     for (const std::string& line : gcode_lines)
     {
-      _parser.parse_line(line, boost::bind(&GCodeTimeEstimator::_process_gcode_line, this, _1, _2));
+      _parser.parse_line(line, 
+        [this](GCodeReader &reader, const GCodeReader::GCodeLine &line)
+          { this->_process_gcode_line(reader, line); });
     }
     _calculate_time();
     reset();
@@ -168,7 +169,21 @@ namespace Slic3r {
   void GCodeTimeEstimator::add_gcode_line(const std::string& gcode_line)
   {
     PROFILE_FUNC();
-    _parser.parse_line(gcode_line, boost::bind(&GCodeTimeEstimator::_process_gcode_line, this, _1, _2));
+    _parser.parse_line(gcode_line, 
+      [this](GCodeReader &reader, const GCodeReader::GCodeLine &line)
+        { this->_process_gcode_line(reader, line); });
+  }
+
+  void GCodeTimeEstimator::add_gcode_block(const char *ptr)
+  {
+    PROFILE_FUNC();
+    GCodeReader::GCodeLine gline;
+    for (; *ptr != 0;) {
+      gline.reset();
+      ptr = _parser.parse_line(ptr, gline, 
+        [this](GCodeReader &reader, const GCodeReader::GCodeLine &line)
+          { this->_process_gcode_line(reader, line); });
+    }
   }
 
   void GCodeTimeEstimator::calculate_time()
@@ -406,13 +421,14 @@ namespace Slic3r {
   void GCodeTimeEstimator::_process_gcode_line(GCodeReader&, const GCodeReader::GCodeLine& line)
   {
     PROFILE_FUNC();
-    if (line.cmd.length() > 1)
+    std::string cmd = line.cmd();
+    if (cmd.length() > 1)
     {
-      switch (::toupper(line.cmd[0]))
+      switch (::toupper(cmd[0]))
       {
       case 'G':
         {
-          switch (::atoi(&line.cmd[1]))
+          switch (::atoi(&cmd[1]))
           {
           case 1: // Move
             {
@@ -460,7 +476,7 @@ namespace Slic3r {
         }
       case 'M':
         {
-          switch (::atoi(&line.cmd[1]))
+          switch (::atoi(&cmd[1]))
           {
           case 82: // Set extruder to absolute mode
             {
@@ -514,9 +530,9 @@ namespace Slic3r {
   float axis_absolute_position_from_G1_line(GCodeTimeEstimator::EAxis axis, const GCodeReader::GCodeLine& lineG1, GCodeTimeEstimator::EUnits units, GCodeTimeEstimator::EPositioningType type, float current_absolute_position)
   {
     float lengthsScaleFactor = (units == GCodeTimeEstimator::Inches) ? INCHES_TO_MM : 1.0f;
-    if (lineG1.has(AXIS_STR[axis]))
+    if (lineG1.has(Slic3r::Axis(axis)))
     {
-      float ret = lineG1.get_float(AXIS_STR[axis]) * lengthsScaleFactor;
+      float ret = lineG1.value(Slic3r::Axis(axis)) * lengthsScaleFactor;
       return (type == GCodeTimeEstimator::Absolute) ? ret : current_absolute_position + ret;
     }
     else
@@ -534,8 +550,8 @@ namespace Slic3r {
     }
 
     // updates feedrate from line, if present
-    if (line.has('F'))
-      set_feedrate(std::max(line.get_float('F') * MMMIN_TO_MMSEC, get_minimum_feedrate()));
+    if (line.has_f())
+      set_feedrate(std::max(line.f() * MMMIN_TO_MMSEC, get_minimum_feedrate()));
 
     // fills block data
     Block block;
@@ -682,15 +698,16 @@ namespace Slic3r {
     }
 
     // adds block to blocks list
-    _blocks.push_back(block);
+    _blocks.emplace_back(block);
   }
 
   void GCodeTimeEstimator::_processG4(const GCodeReader::GCodeLine& line)
   {
     EDialect dialect = get_dialect();
 
-    if (line.has('P'))
-      add_additional_time(line.get_float('P') * MILLISEC_TO_SEC);
+    float value;
+    if (line.has_value('P', value))
+      add_additional_time(value * MILLISEC_TO_SEC);
 
     // see: http://reprap.org/wiki/G-code#G4:_Dwell
     if ((dialect == Repetier) ||
@@ -698,8 +715,8 @@ namespace Slic3r {
         (dialect == Smoothieware) ||
         (dialect == RepRapFirmware))
     {
-      if (line.has('S'))
-        add_additional_time(line.get_float('S'));
+      if (line.has_value('S', value))
+        add_additional_time(value);
     }
   }
 
@@ -745,27 +762,27 @@ namespace Slic3r {
     float lengthsScaleFactor = (get_units() == Inches) ? INCHES_TO_MM : 1.0f;
     bool anyFound = false;
 
-    if (line.has('X'))
+    if (line.has_x())
     {
-      set_axis_position(X, line.get_float('X') * lengthsScaleFactor);
+      set_axis_position(X, line.x() * lengthsScaleFactor);
       anyFound = true;
     }
 
-    if (line.has('Y'))
+    if (line.has_y())
     {
-      set_axis_position(Y, line.get_float('Y') * lengthsScaleFactor);
+      set_axis_position(Y, line.y() * lengthsScaleFactor);
       anyFound = true;
     }
 
-    if (line.has('Z'))
+    if (line.has_z())
     {
-      set_axis_position(Z, line.get_float('Z') * lengthsScaleFactor);
+      set_axis_position(Z, line.z() * lengthsScaleFactor);
       anyFound = true;
     }
 
-    if (line.has('E'))
+    if (line.has_e())
     {
-      set_axis_position(E, line.get_float('E') * lengthsScaleFactor);
+      set_axis_position(E, line.e() * lengthsScaleFactor);
       anyFound = true;
     }
 
@@ -790,17 +807,17 @@ namespace Slic3r {
     // see http://reprap.org/wiki/G-code#M201:_Set_max_printing_acceleration
     float factor = ((dialect != RepRapFirmware) && (get_units() == GCodeTimeEstimator::Inches)) ? INCHES_TO_MM : 1.0f;
 
-    if (line.has('X'))
-      set_axis_max_acceleration(X, line.get_float('X') * factor);
+    if (line.has_x())
+      set_axis_max_acceleration(X, line.x() * factor);
 
-    if (line.has('Y'))
-      set_axis_max_acceleration(Y, line.get_float('Y') * factor);
+    if (line.has_y())
+      set_axis_max_acceleration(Y, line.y() * factor);
 
-    if (line.has('Z'))
-      set_axis_max_acceleration(Z, line.get_float('Z') * factor);
+    if (line.has_z())
+      set_axis_max_acceleration(Z, line.z() * factor);
 
-    if (line.has('E'))
-      set_axis_max_acceleration(E, line.get_float('E') * factor);
+    if (line.has_e())
+      set_axis_max_acceleration(E, line.e() * factor);
   }
 
   void GCodeTimeEstimator::_processM203(const GCodeReader::GCodeLine& line)
@@ -814,66 +831,68 @@ namespace Slic3r {
     // see http://reprap.org/wiki/G-code#M203:_Set_maximum_feedrate
     float factor = (dialect == Marlin) ? 1.0f : MMMIN_TO_MMSEC;
 
-    if (line.has('X'))
-      set_axis_max_feedrate(X, line.get_float('X') * factor);
+    if (line.has_x())
+      set_axis_max_feedrate(X, line.x() * factor);
 
-    if (line.has('Y'))
-      set_axis_max_feedrate(Y, line.get_float('Y') * factor);
+    if (line.has_y())
+      set_axis_max_feedrate(Y, line.y() * factor);
 
-    if (line.has('Z'))
-      set_axis_max_feedrate(Z, line.get_float('Z') * factor);
+    if (line.has_z())
+      set_axis_max_feedrate(Z, line.z() * factor);
 
-    if (line.has('E'))
-      set_axis_max_feedrate(E, line.get_float('E') * factor);
+    if (line.has_e())
+      set_axis_max_feedrate(E, line.e() * factor);
   }
 
   void GCodeTimeEstimator::_processM204(const GCodeReader::GCodeLine& line)
   {
-    if (line.has('S'))
-      set_acceleration(line.get_float('S'));
+    float value;
+    if (line.has_value('S', value))
+      set_acceleration(value);
 
-    if (line.has('T'))
-      set_retract_acceleration(line.get_float('T'));
+    if (line.has_value('T', value))
+      set_retract_acceleration(value);
   }
 
   void GCodeTimeEstimator::_processM205(const GCodeReader::GCodeLine& line)
   {
-    if (line.has('X'))
+    if (line.has_x())
     {
-      float max_jerk = line.get_float('X');
+      float max_jerk = line.x();
       set_axis_max_jerk(X, max_jerk);
       set_axis_max_jerk(Y, max_jerk);
     }
 
-    if (line.has('Y'))
-      set_axis_max_jerk(Y, line.get_float('Y'));
+    if (line.has_y())
+      set_axis_max_jerk(Y, line.y());
 
-    if (line.has('Z'))
-      set_axis_max_jerk(Z, line.get_float('Z'));
+    if (line.has_z())
+      set_axis_max_jerk(Z, line.z());
 
-    if (line.has('E'))
-      set_axis_max_jerk(E, line.get_float('E'));
+    if (line.has_e())
+      set_axis_max_jerk(E, line.e());
 
-    if (line.has('S'))
-      set_minimum_feedrate(line.get_float('S'));
+    float value;
+    if (line.has_value('S', value))
+      set_minimum_feedrate(value);
 
-    if (line.has('T'))
-      set_minimum_travel_feedrate(line.get_float('T'));
+    if (line.has_value('T', value))
+      set_minimum_travel_feedrate(value);
   }
 
   void GCodeTimeEstimator::_processM566(const GCodeReader::GCodeLine& line)
   {
-    if (line.has('X'))
-      set_axis_max_jerk(X, line.get_float('X') * MMMIN_TO_MMSEC);
+    if (line.has_x())
+      set_axis_max_jerk(X, line.x() * MMMIN_TO_MMSEC);
 
-    if (line.has('Y'))
-      set_axis_max_jerk(Y, line.get_float('Y') * MMMIN_TO_MMSEC);
+    if (line.has_y())
+      set_axis_max_jerk(Y, line.y() * MMMIN_TO_MMSEC);
 
-    if (line.has('Z'))
-      set_axis_max_jerk(Z, line.get_float('Z') * MMMIN_TO_MMSEC);
+    if (line.has_z())
+      set_axis_max_jerk(Z, line.z() * MMMIN_TO_MMSEC);
 
-    if (line.has('E'))
-      set_axis_max_jerk(E, line.get_float('E') * MMMIN_TO_MMSEC);
+    if (line.has_e())
+      set_axis_max_jerk(E, line.e() * MMMIN_TO_MMSEC);
   }
 
   void GCodeTimeEstimator::_forward_pass()
diff --git a/xs/src/libslic3r/GCodeTimeEstimator.hpp b/xs/src/libslic3r/GCodeTimeEstimator.hpp
index 894d00ef3..84c6de5fc 100644
--- a/xs/src/libslic3r/GCodeTimeEstimator.hpp
+++ b/xs/src/libslic3r/GCodeTimeEstimator.hpp
@@ -183,6 +183,9 @@ namespace Slic3r {
     // Adds the given gcode line
     void add_gcode_line(const std::string& gcode_line);
 
+    void add_gcode_block(const char *ptr);
+    void add_gcode_block(const std::string &str) { this->add_gcode_block(str.c_str()); }
+
     // Calculates the time estimate from the gcode lines added using add_gcode_line()
     void calculate_time();
 
diff --git a/xs/src/libslic3r/libslic3r.h b/xs/src/libslic3r/libslic3r.h
index 1a02605e1..7c694b05e 100644
--- a/xs/src/libslic3r/libslic3r.h
+++ b/xs/src/libslic3r/libslic3r.h
@@ -102,7 +102,7 @@ inline std::string debug_out_path(const char *name, ...)
 
 namespace Slic3r {
 
-enum Axis { X=0, Y, Z };
+enum Axis { X=0, Y, Z, E, F, NUM_AXES };
 
 template <class T>
 inline void append_to(std::vector<T> &dst, const std::vector<T> &src)