diff --git a/xs/src/libslic3r/GCode.cpp b/xs/src/libslic3r/GCode.cpp
index de498fce6..2304fad07 100644
--- a/xs/src/libslic3r/GCode.cpp
+++ b/xs/src/libslic3r/GCode.cpp
@@ -1928,8 +1928,7 @@ std::string GCode::travel_to(const Point &point, ExtrusionRole role, std::string
     return gcode;
 }
 
-bool
-GCode::needs_retraction(const Polyline &travel, ExtrusionRole role)
+bool GCode::needs_retraction(const Polyline &travel, ExtrusionRole role)
 {
     if (travel.length() < scale_(EXTRUDER_CONFIG(retract_before_travel))) {
         // skip retraction if the move is shorter than the configured threshold
@@ -1946,14 +1945,12 @@ GCode::needs_retraction(const Polyline &travel, ExtrusionRole role)
             return false;
     }
 
-    if (m_config.only_retract_when_crossing_perimeters && m_layer != nullptr) {
-        if (m_config.fill_density.value > 0
-            && m_layer->any_internal_region_slice_contains(travel)) {
-            /*  skip retraction if travel is contained in an internal slice *and*
-                internal infill is enabled (so that stringing is entirely not visible)  */
-            return false;
-        }
-    }
+    if (m_config.only_retract_when_crossing_perimeters && m_layer != nullptr &&
+        m_config.fill_density.value > 0 && m_layer->any_internal_region_slice_contains(travel))
+        // Skip retraction if travel is contained in an internal slice *and*
+        // internal infill is enabled (so that stringing is entirely not visible).
+        //FIXME any_internal_region_slice_contains() is potentionally very slow, it shall test for the bounding boxes first.
+        return false;
     
     // retract if only_retract_when_crossing_perimeters is disabled or doesn't apply
     return true;
diff --git a/xs/src/libslic3r/Layer.cpp b/xs/src/libslic3r/Layer.cpp
index 94413c2bb..cfa66f9eb 100644
--- a/xs/src/libslic3r/Layer.cpp
+++ b/xs/src/libslic3r/Layer.cpp
@@ -70,27 +70,6 @@ void Layer::merge_slices()
     }
 }
 
-template <class T>
-bool Layer::any_internal_region_slice_contains(const T &item) const
-{
-    FOREACH_LAYERREGION(this, layerm) {
-        if ((*layerm)->slices.any_internal_contains(item)) return true;
-    }
-    return false;
-}
-template bool Layer::any_internal_region_slice_contains<Polyline>(const Polyline &item) const;
-
-template <class T>
-bool Layer::any_bottom_region_slice_contains(const T &item) const
-{
-    FOREACH_LAYERREGION(this, layerm) {
-        if ((*layerm)->slices.any_bottom_contains(item)) return true;
-    }
-    return false;
-}
-template bool Layer::any_bottom_region_slice_contains<Polyline>(const Polyline &item) const;
-
-
 // Here the perimeters are created cummulatively for all layer regions sharing the same parameters influencing the perimeters.
 // The perimeter paths and the thin fills (ExtrusionEntityCollection) are assigned to the first compatible layer region.
 // The resulting fill surface is split back among the originating regions.
diff --git a/xs/src/libslic3r/Layer.hpp b/xs/src/libslic3r/Layer.hpp
index 2f0228453..0bb76fe13 100644
--- a/xs/src/libslic3r/Layer.hpp
+++ b/xs/src/libslic3r/Layer.hpp
@@ -115,8 +115,14 @@ public:
     
     void make_slices();
     void merge_slices();
-    template <class T> bool any_internal_region_slice_contains(const T &item) const;
-    template <class T> bool any_bottom_region_slice_contains(const T &item) const;
+    template <class T> bool any_internal_region_slice_contains(const T &item) const {
+        for (const LayerRegion *layerm : this->regions) if (layerm->slices.any_internal_contains(item)) return true;
+        return false;
+    }
+    template <class T> bool any_bottom_region_slice_contains(const T &item) const {
+        for (const LayerRegion *layerm : this->regions) if (layerm->slices.any_bottom_contains(item)) return true;
+        return false;
+    }
     void make_perimeters();
     void make_fills();
 
diff --git a/xs/src/libslic3r/SurfaceCollection.cpp b/xs/src/libslic3r/SurfaceCollection.cpp
index 70272fede..42ddf9574 100644
--- a/xs/src/libslic3r/SurfaceCollection.cpp
+++ b/xs/src/libslic3r/SurfaceCollection.cpp
@@ -54,28 +54,6 @@ SurfaceCollection::group(std::vector<SurfacesPtr> *retval)
     }
 }
 
-template <class T>
-bool
-SurfaceCollection::any_internal_contains(const T &item) const
-{
-    for (Surfaces::const_iterator surface = this->surfaces.begin(); surface != this->surfaces.end(); ++surface) {
-        if (surface->is_internal() && surface->expolygon.contains(item)) return true;
-    }
-    return false;
-}
-template bool SurfaceCollection::any_internal_contains<Polyline>(const Polyline &item) const;
-
-template <class T>
-bool
-SurfaceCollection::any_bottom_contains(const T &item) const
-{
-    for (Surfaces::const_iterator surface = this->surfaces.begin(); surface != this->surfaces.end(); ++surface) {
-        if (surface->is_bottom() && surface->expolygon.contains(item)) return true;
-    }
-    return false;
-}
-template bool SurfaceCollection::any_bottom_contains<Polyline>(const Polyline &item) const;
-
 SurfacesPtr
 SurfaceCollection::filter_by_type(const SurfaceType type)
 {
diff --git a/xs/src/libslic3r/SurfaceCollection.hpp b/xs/src/libslic3r/SurfaceCollection.hpp
index 41e4c81b9..0edca6a5a 100644
--- a/xs/src/libslic3r/SurfaceCollection.hpp
+++ b/xs/src/libslic3r/SurfaceCollection.hpp
@@ -19,8 +19,14 @@ public:
     operator ExPolygons() const;
     void simplify(double tolerance);
     void group(std::vector<SurfacesPtr> *retval);
-    template <class T> bool any_internal_contains(const T &item) const;
-    template <class T> bool any_bottom_contains(const T &item) const;
+    template <class T> bool any_internal_contains(const T &item) const {
+        for (const Surface &surface : this->surfaces) if (surface.is_internal() && surface.expolygon.contains(item)) return true;
+        return false;
+    }
+    template <class T> bool any_bottom_contains(const T &item) const {
+        for (const Surface &surface : this->surfaces) if (surface.is_bottom() && surface.expolygon.contains(item)) return true;
+        return false;
+    }
     SurfacesPtr filter_by_type(const SurfaceType type);
     SurfacesPtr filter_by_types(const SurfaceType *types, int ntypes);
     void keep_type(const SurfaceType type);
diff --git a/xs/xsp/Layer.xsp b/xs/xsp/Layer.xsp
index 55e52eca4..896712ffc 100644
--- a/xs/xsp/Layer.xsp
+++ b/xs/xsp/Layer.xsp
@@ -87,10 +87,6 @@
     
     void make_slices();
     void merge_slices();
-    bool any_internal_region_slice_contains_polyline(Polyline* polyline)
-        %code%{ RETVAL = THIS->any_internal_region_slice_contains(*polyline); %};
-    bool any_bottom_region_slice_contains_polyline(Polyline* polyline)
-        %code%{ RETVAL = THIS->any_bottom_region_slice_contains(*polyline); %};
     void make_perimeters();
     void make_fills();