diff --git a/src/slic3r/GUI/3DBed.cpp b/src/slic3r/GUI/3DBed.cpp
index 545f5ab1038..8488c1148fd 100644
--- a/src/slic3r/GUI/3DBed.cpp
+++ b/src/slic3r/GUI/3DBed.cpp
@@ -311,10 +311,11 @@ void Bed3D::init_triangles()
     if (triangles.empty() || triangles.size() % 3 != 0)
         return;
 
-    const GLModel::Geometry::EIndexType index_type = (triangles.size() < 65536) ? GLModel::Geometry::EIndexType::USHORT : GLModel::Geometry::EIndexType::UINT;
-
     GLModel::Geometry init_data;
+    const GLModel::Geometry::EIndexType index_type = (triangles.size() < 65536) ? GLModel::Geometry::EIndexType::USHORT : GLModel::Geometry::EIndexType::UINT;
     init_data.format = { GLModel::Geometry::EPrimitiveType::Triangles, GLModel::Geometry::EVertexLayout::P3T2, index_type };
+    init_data.reserve_vertices(triangles.size());
+    init_data.reserve_indices(triangles.size() / 3);
 
     Vec2f min = triangles.front();
     Vec2f max = min;
@@ -330,6 +331,7 @@ void Bed3D::init_triangles()
     Vec2f inv_size = size.cwiseInverse();
     inv_size.y() *= -1.0f;
 
+    // vertices + indices
     unsigned int vertices_counter = 0;
     for (const Vec2f& v : triangles) {
         const Vec3f p = { v.x(), v.y(), GROUND_Z };
@@ -378,10 +380,11 @@ void Bed3D::init_gridlines()
     Lines contour_lines = to_lines(m_contour);
     std::copy(contour_lines.begin(), contour_lines.end(), std::back_inserter(gridlines));
 
-    const GLModel::Geometry::EIndexType index_type = (gridlines.size() < 65536 / 2) ? GLModel::Geometry::EIndexType::USHORT : GLModel::Geometry::EIndexType::UINT;
-
     GLModel::Geometry init_data;
+    const GLModel::Geometry::EIndexType index_type = (2 * gridlines.size() < 65536) ? GLModel::Geometry::EIndexType::USHORT : GLModel::Geometry::EIndexType::UINT;
     init_data.format = { GLModel::Geometry::EPrimitiveType::Lines, GLModel::Geometry::EVertexLayout::P3, index_type };
+    init_data.reserve_vertices(2 * gridlines.size());
+    init_data.reserve_indices(2 * gridlines.size());
 
     for (const Line& l : gridlines) {
         init_data.add_vertex(Vec3f(unscale<float>(l.a.x()), unscale<float>(l.a.y()), GROUND_Z));
diff --git a/src/slic3r/GUI/3DScene.cpp b/src/slic3r/GUI/3DScene.cpp
index 846c8289433..339754790fb 100644
--- a/src/slic3r/GUI/3DScene.cpp
+++ b/src/slic3r/GUI/3DScene.cpp
@@ -400,7 +400,8 @@ void GLVolume::NonManifoldEdges::update()
             if (!edges.empty()) {
                 GUI::GLModel::Geometry init_data;
 #if ENABLE_GLBEGIN_GLEND_REMOVAL
-                init_data.format = { GUI::GLModel::Geometry::EPrimitiveType::Lines, GUI::GLModel::Geometry::EVertexLayout::P3, GUI::GLModel::Geometry::EIndexType::UINT };
+                const GUI::GLModel::Geometry::EIndexType index_type = (2 * edges.size() < 65536) ? GUI::GLModel::Geometry::EIndexType::USHORT : GUI::GLModel::Geometry::EIndexType::UINT;
+                init_data.format = { GUI::GLModel::Geometry::EPrimitiveType::Lines, GUI::GLModel::Geometry::EVertexLayout::P3, index_type };
                 init_data.reserve_vertices(2 * edges.size());
                 init_data.reserve_indices(2 * edges.size());
 
@@ -410,7 +411,10 @@ void GLVolume::NonManifoldEdges::update()
                     init_data.add_vertex((Vec3f)mesh.its.vertices[edge.first].cast<float>());
                     init_data.add_vertex((Vec3f)mesh.its.vertices[edge.second].cast<float>());
                     vertices_count += 2;
-                    init_data.add_uint_line(vertices_count - 2, vertices_count - 1);
+                    if (index_type == GUI::GLModel::Geometry::EIndexType::USHORT)
+                        init_data.add_ushort_line((unsigned short)vertices_count - 2, (unsigned short)vertices_count - 1);
+                    else
+                        init_data.add_uint_line(vertices_count - 2, vertices_count - 1);
                 }
                 m_model.init_from(std::move(init_data));
 #else
diff --git a/src/slic3r/GUI/GLCanvas3D.cpp b/src/slic3r/GUI/GLCanvas3D.cpp
index 871680cb523..95600c074a8 100644
--- a/src/slic3r/GUI/GLCanvas3D.cpp
+++ b/src/slic3r/GUI/GLCanvas3D.cpp
@@ -447,7 +447,8 @@ void GLCanvas3D::LayersEditing::render_profile(const Rect& bar_rect)
         m_profile.profile.reset();
 
         GLModel::Geometry init_data;
-        init_data.format = { GLModel::Geometry::EPrimitiveType::LineStrip, GLModel::Geometry::EVertexLayout::P2, GLModel::Geometry::EIndexType::UINT };
+        const GLModel::Geometry::EIndexType index_type = (m_layer_height_profile.size() / 2 < 65536) ? GLModel::Geometry::EIndexType::USHORT : GLModel::Geometry::EIndexType::UINT;
+        init_data.format = { GLModel::Geometry::EPrimitiveType::LineStrip, GLModel::Geometry::EVertexLayout::P2, index_type };
         init_data.color = ColorRGBA::BLUE();
         init_data.reserve_vertices(m_layer_height_profile.size() / 2);
         init_data.reserve_indices(m_layer_height_profile.size() / 2);
@@ -456,7 +457,10 @@ void GLCanvas3D::LayersEditing::render_profile(const Rect& bar_rect)
         for (unsigned int i = 0; i < (unsigned int)m_layer_height_profile.size(); i += 2) {
             init_data.add_vertex(Vec2f(bar_rect.get_left() + float(m_layer_height_profile[i + 1]) * scale_x,
                                        bar_rect.get_bottom() + float(m_layer_height_profile[i]) * scale_y));
-            init_data.add_uint_index(i / 2);
+            if (index_type == GLModel::Geometry::EIndexType::USHORT)
+                init_data.add_ushort_index((unsigned short)i / 2);
+            else
+                init_data.add_uint_index(i / 2);
         }
 
         m_profile.profile.init_from(std::move(init_data));
@@ -898,6 +902,8 @@ void GLCanvas3D::SequentialPrintClearance::set_polygons(const Polygons& polygons
         unsigned int vertices_counter = 0;
         for (const ExPolygon& poly : polygons_union) {
             const std::vector<Vec3d> triangulation = triangulate_expolygon_3d(poly);
+            fill_data.reserve_vertices(fill_data.vertices_count() + triangulation.size());
+            fill_data.reserve_indices(fill_data.indices_count() + triangulation.size());
             for (const Vec3d& v : triangulation) {
                 fill_data.add_vertex((Vec3f)(v.cast<float>() + 0.0125f * Vec3f::UnitZ())); // add a small positive z to avoid z-fighting
                 ++vertices_counter;
diff --git a/src/slic3r/GUI/Gizmos/GLGizmoFlatten.cpp b/src/slic3r/GUI/Gizmos/GLGizmoFlatten.cpp
index 9218558b71b..0956a9047b0 100644
--- a/src/slic3r/GUI/Gizmos/GLGizmoFlatten.cpp
+++ b/src/slic3r/GUI/Gizmos/GLGizmoFlatten.cpp
@@ -370,9 +370,9 @@ void GLGizmoFlatten::update_planes()
         for (size_t i = 0; i < plane.vertices.size(); ++i) {
             init_data.add_vertex((Vec3f)plane.vertices[i].cast<float>(), (Vec3f)plane.normal.cast<float>());
             if (index_type == GLModel::Geometry::EIndexType::USHORT)
-                init_data.add_ushort_index(i);
+                init_data.add_ushort_index((unsigned short)i);
             else
-                init_data.add_uint_index(i);
+                init_data.add_uint_index((unsigned int)i);
         }
         plane.vbo.init_from(std::move(init_data));
 #else