diff --git a/src/libslic3r/GCode/GCodeProcessor.cpp b/src/libslic3r/GCode/GCodeProcessor.cpp
index e03be228d0..505a28335d 100644
--- a/src/libslic3r/GCode/GCodeProcessor.cpp
+++ b/src/libslic3r/GCode/GCodeProcessor.cpp
@@ -2582,8 +2582,12 @@ void GCodeProcessorResult::reset() {
     //BBS: add mutex for protection of gcode result
     lock();
 
-    moves.clear();
-    lines_ends.clear();
+    // release rather than clear: these two are sized by the print - one entry per move and one
+    // per g-code line - and a reset is where the memory is expected to go back to the allocator
+    // (see BackgroundSlicingProcess::apply()). The capacity would not be reused anyway: the
+    // result is refilled by move-assigning the processor's own result.
+    moves = std::vector<MoveVertex>();
+    lines_ends = std::vector<size_t>();
     printable_area = Pointfs();
     //BBS: add bed exclude area
     bed_exclude_area = Pointfs();
diff --git a/src/libslic3r/GCode/GCodeProcessor.hpp b/src/libslic3r/GCode/GCodeProcessor.hpp
index 192a80a43d..a99a5188d6 100644
--- a/src/libslic3r/GCode/GCodeProcessor.hpp
+++ b/src/libslic3r/GCode/GCodeProcessor.hpp
@@ -369,6 +369,56 @@ class Print;
             initial_layer_time = other.initial_layer_time;
 #if ENABLE_GCODE_VIEWER_STATISTICS
             time = other.time;
+#endif
+            return *this;
+        }
+        // Orca: the user-declared copy assignment above suppresses the implicit move assignment, so
+        // `*result = std::move(processor.extract_result())` used to deep copy 'moves' (one MoveVertex
+        // per move, gigabytes on a large print) while the source stayed alive. This moves exactly the
+        // same members as the copy above, with the same omissions, so the members the copy leaves
+        // untouched on the target are left untouched here too.
+        GCodeProcessorResult& operator=(GCodeProcessorResult &&other)
+        {
+            filename = std::move(other.filename);
+            id = other.id;
+            moves = std::move(other.moves);
+            lines_ends = std::move(other.lines_ends);
+            printable_area = std::move(other.printable_area);
+            bed_exclude_area = std::move(other.bed_exclude_area);
+            wrapping_exclude_area = std::move(other.wrapping_exclude_area);
+            toolpath_outside = other.toolpath_outside;
+            label_object_enabled = other.label_object_enabled;
+            long_retraction_when_cut = other.long_retraction_when_cut;
+            timelapse_warning_code = other.timelapse_warning_code;
+            printable_height = other.printable_height;
+            settings_ids = std::move(other.settings_ids);
+            filaments_count = other.filaments_count;
+            extruder_colors = std::move(other.extruder_colors);
+            filament_diameters = std::move(other.filament_diameters);
+            filament_densities = std::move(other.filament_densities);
+            filament_costs = std::move(other.filament_costs);
+            print_statistics = std::move(other.print_statistics);
+            custom_gcode_per_print_z = std::move(other.custom_gcode_per_print_z);
+            spiral_vase_mode = other.spiral_vase_mode;
+            warnings = std::move(other.warnings);
+            bed_type = other.bed_type;
+            gcode_check_result = std::move(other.gcode_check_result);
+            limit_filament_maps = std::move(other.limit_filament_maps);
+            filament_printable_reuslt = std::move(other.filament_printable_reuslt);
+            nozzle_group_result = std::move(other.nozzle_group_result);
+            extruder_types = std::move(other.extruder_types);
+            printer_extruder_variant = std::move(other.printer_extruder_variant);
+            printer_extruder_id = std::move(other.printer_extruder_id);
+            layer_filaments = std::move(other.layer_filaments);
+            filament_change_sequence = std::move(other.filament_change_sequence);
+            used_mixed_filaments = std::move(other.used_mixed_filaments);
+            nozzle_change_sequence = std::move(other.nozzle_change_sequence);
+            optimal_assignment = std::move(other.optimal_assignment);
+            filament_change_count_map = std::move(other.filament_change_count_map);
+            skippable_part_time = std::move(other.skippable_part_time);
+            initial_layer_time = other.initial_layer_time;
+#if ENABLE_GCODE_VIEWER_STATISTICS
+            time = other.time;
 #endif
             return *this;
         }
diff --git a/src/libvgcode/src/ViewerImpl.cpp b/src/libvgcode/src/ViewerImpl.cpp
index 8212717931..e3e106bb59 100644
--- a/src/libvgcode/src/ViewerImpl.cpp
+++ b/src/libvgcode/src/ViewerImpl.cpp
@@ -883,15 +883,17 @@ void ViewerImpl::reset()
     m_used_extruders.clear();
     m_total_time = { 0.0f, 0.0f };
     m_travels_time = { 0.0f, 0.0f };
-    m_vertices.clear();
-    m_vertices_colors.clear();
     // swap rather than clear: these are sized by the print, and a reset means the memory
     // should go back, not sit reserved until the next load
+    std::vector<PathVertex>().swap(m_vertices);
+    std::vector<float>().swap(m_vertices_colors);
     for (std::vector<float>& times : m_layer_start_times)
         std::vector<float>().swap(times);
     std::vector<uint32_t>().swap(m_layer_first_vertex);
     std::vector<float>().swap(m_colors_scratch);
-    m_valid_lines_bitset.clear();
+    // BitSet::clear() only zeroes the bits, it keeps the blocks allocated; load() builds a new
+    // bitset anyway and it is never read while m_vertices is empty
+    m_valid_lines_bitset = BitSet<>();
 #if VGCODE_ENABLE_COG_AND_TOOL_MARKERS
     m_cog_marker.reset();
 #endif // VGCODE_ENABLE_COG_AND_TOOL_MARKERS
@@ -1812,6 +1814,7 @@ size_t ViewerImpl::get_used_cpu_memory() const
     ret += sizeof(m_extrusion_roles_colors);
     ret += sizeof(m_options_colors);
     ret += STDVEC_MEMSIZE(m_vertices, PathVertex);
+    ret += STDVEC_MEMSIZE(m_vertices_colors, float);
     for (const std::vector<float>& times : m_layer_start_times)
         ret += STDVEC_MEMSIZE(times, float);
     ret += STDVEC_MEMSIZE(m_layer_first_vertex, uint32_t);