diff --git a/src/slic3r/GUI/3DScene.cpp b/src/slic3r/GUI/3DScene.cpp
index 01c6248129..24fc80b01e 100644
--- a/src/slic3r/GUI/3DScene.cpp
+++ b/src/slic3r/GUI/3DScene.cpp
@@ -751,7 +751,7 @@ void GLVolumeCollection::render(GLVolumeCollection::ERenderType type, bool disab
         return;
 
     GLShaderProgram* curr_shader = GUI::wxGetApp().get_current_shader();
-    GLShaderProgram* sink_shader  = GUI::wxGetApp().get_shader("flat");
+    GLShaderProgram* sink_shader = GUI::wxGetApp().get_shader("flat");
 #if SLIC3R_OPENGL_ES
     GLShaderProgram* edges_shader = GUI::wxGetApp().get_shader("dashed_lines");
 #else
@@ -774,9 +774,34 @@ void GLVolumeCollection::render(GLVolumeCollection::ERenderType type, bool disab
     if (disable_cullface)
         glsafe(::glDisable(GL_CULL_FACE));
 
+
+    // This block is here to render the pained triangles. It is not very nice, but it works.
+    // There is a cache that holds the OpenGL models of the painted areas to render, one for
+    // each ModelVolume. The cache is invalidated based on changes in extruder_colors,
+    // default extruder idx and timestamp of the painted data. The data belonging to objects
+    // // which no longer exist are removed from the cache periodically.
     const ModelObjectPtrs& model_objects = GUI::wxGetApp().model().objects;
     const std::vector<ColorRGBA> extruders_colors = GUI::wxGetApp().plater()->get_extruder_colors_from_plater_config();
     const bool is_render_as_mmu_painted_enabled = !model_objects.empty() && !extruders_colors.empty();
+    struct MMPaintCachePerVolume {
+        size_t extruder_id;
+        std::unique_ptr<GUI::TriangleSelectorMmGui> triangle_selector_mm;
+        std::chrono::system_clock::time_point time_used;
+        uint64_t mm_timestamp;
+    };
+    struct MMPaintCache {
+        std::vector<ColorRGBA> extruders_colors;
+        std::map<ObjectID, MMPaintCachePerVolume> volume_data;
+    };
+    static MMPaintCache mm_paint_cache;
+    if (mm_paint_cache.extruders_colors != extruders_colors) {
+        mm_paint_cache.extruders_colors = extruders_colors;
+        mm_paint_cache.volume_data.clear();
+    }
+    auto time_now = std::chrono::system_clock::now();
+
+
+
 
     for (GLVolumeWithIdAndZ& volume : to_render) {
         if (!volume.first->is_active)
@@ -788,8 +813,8 @@ void GLVolumeCollection::render(GLVolumeCollection::ERenderType type, bool disab
         const int obj_idx = volume.first->object_idx();
         const int vol_idx = volume.first->volume_idx();
         const bool render_as_mmu_painted = is_render_as_mmu_painted_enabled && !volume.first->selected &&
-          !volume.first->is_outside && !volume.first->is_wipe_tower && obj_idx >= 0 && vol_idx >= 0 &&
-          !model_objects[obj_idx]->volumes[vol_idx]->mm_segmentation_facets.empty();
+            !volume.first->is_outside && volume.first->hover == GLVolume::HS_None && !volume.first->is_wipe_tower && obj_idx >= 0 && vol_idx >= 0 &&
+            !model_objects[obj_idx]->volumes[vol_idx]->mm_segmentation_facets.empty();
         volume.first->set_render_color(true);
 
         // render sinking contours of non-hovered volumes
@@ -827,13 +852,30 @@ void GLVolumeCollection::render(GLVolumeCollection::ERenderType type, bool disab
 
             const ModelVolume& model_volume = *model_objects[obj_idx]->volumes[vol_idx];
             const size_t extruder_idx = ModelVolume::get_extruder_color_idx(model_volume, GUI::wxGetApp().extruders_edited_cnt());
-            GUI::TriangleSelectorMmGui ts(model_volume.mesh(), extruders_colors, extruders_colors[extruder_idx]);
-            ts.deserialize(model_volume.mm_segmentation_facets.get_data(), true);
-            ts.request_update_render_data();
-            ts.render(nullptr, world_matrix);
+
+
+            // This block retrieves the painted geometry from the cache or adds it to it.
+            ObjectID vol_id = model_volume.id();
+            auto it = mm_paint_cache.volume_data.find(vol_id);
+            GUI::TriangleSelectorMmGui* ts = nullptr;
+            uint64_t timestamp = model_volume.mm_segmentation_facets.timestamp();
+            if (it == mm_paint_cache.volume_data.end() || it->second.extruder_id != extruder_idx || timestamp != it->second.mm_timestamp) {
+                auto ts_uptr = std::make_unique<GUI::TriangleSelectorMmGui>(model_volume.mesh(), mm_paint_cache.extruders_colors, mm_paint_cache.extruders_colors[extruder_idx]);
+                ts = ts_uptr.get();
+                ts->deserialize(model_volume.mm_segmentation_facets.get_data(), true);
+                ts->request_update_render_data();
+                mm_paint_cache.volume_data[vol_id] = MMPaintCachePerVolume{ extruder_idx, std::move(ts_uptr), std::chrono::system_clock::now(), timestamp };
+            }
+            else {
+                ts = it->second.triangle_selector_mm.get();
+                it->second.time_used = time_now;
+            }
+
+            
+            ts->render(nullptr, world_matrix);
 
             if (is_left_handed)
-              glsafe(::glFrontFace(GL_CCW));
+                glsafe(::glFrontFace(GL_CCW));
 
             shader->stop_using();
         }
@@ -879,6 +921,20 @@ void GLVolumeCollection::render(GLVolumeCollection::ERenderType type, bool disab
         }
     }
 
+
+    // Purge the painted triangles cache from everything that was not used for some time.
+    // Only do this occasionally (once a second).
+    using namespace std::chrono_literals;
+    static auto time_since_last_check = time_now;
+    if (time_now - time_since_last_check > 1000ms)
+        for (auto it = mm_paint_cache.volume_data.begin(); it != mm_paint_cache.volume_data.end(); ) {
+            auto it_delete = it; // The iterator to the deleted element will be invalidated, the others will not.
+            ++it;
+            if (time_now - it_delete->second.time_used > 5000ms)
+                mm_paint_cache.volume_data.erase(it_delete);
+    }
+
+
     if (m_show_sinking_contours) {
         if (sink_shader != nullptr) {
             sink_shader->start_using();