From 2bd868ecd0d1ee0c4a96dfaa16e5130c1f2dd107 Mon Sep 17 00:00:00 2001
From: Kris Austin <kris.austin@gmail.com>
Date: Mon, 5 Oct 2026 19:21:13 -0500
Subject: [PATCH] perf: avoid print config copies to speed up slicing by up to
 5% (#16183)

---
 src/libslic3r/Layer.cpp               | 6 +++---
 src/libslic3r/LayerRegion.cpp         | 6 +++---
 src/libslic3r/Support/TreeSupport.cpp | 4 ++--
 3 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/src/libslic3r/Layer.cpp b/src/libslic3r/Layer.cpp
index 5439e0fa7a..610dd959d2 100644
--- a/src/libslic3r/Layer.cpp
+++ b/src/libslic3r/Layer.cpp
@@ -378,7 +378,7 @@ void Layer::simplify_support_entity_collection(ExtrusionEntityCollection* entity
 //BBS: method to simplify support path
 void Layer::simplify_support_path(ExtrusionPath * path)
 {
-    const auto print_config = this->object()->print()->config();
+    const auto &print_config = this->object()->print()->config();
     const bool spiral_mode = print_config.spiral_mode;
     const bool enable_arc_fitting = print_config.enable_arc_fitting;
     const auto scaled_resolution = scaled<double>(print_config.resolution.value);
@@ -393,7 +393,7 @@ void Layer::simplify_support_path(ExtrusionPath * path)
 //BBS: method to simplify support path
 void Layer::simplify_support_multi_path(ExtrusionMultiPath* multipath)
 {
-    const auto print_config = this->object()->print()->config();
+    const auto &print_config = this->object()->print()->config();
     const bool spiral_mode = print_config.spiral_mode;
     const bool enable_arc_fitting = print_config.enable_arc_fitting;
     const auto scaled_resolution = scaled<double>(print_config.resolution.value);
@@ -410,7 +410,7 @@ void Layer::simplify_support_multi_path(ExtrusionMultiPath* multipath)
 //BBS: method to simplify support path
 void Layer::simplify_support_loop(ExtrusionLoop* loop)
 {
-    const auto print_config = this->object()->print()->config();
+    const auto &print_config = this->object()->print()->config();
     const bool spiral_mode = print_config.spiral_mode;
     const bool enable_arc_fitting = print_config.enable_arc_fitting;
     const auto scaled_resolution = scaled<double>(print_config.resolution.value);
diff --git a/src/libslic3r/LayerRegion.cpp b/src/libslic3r/LayerRegion.cpp
index 99b20e50f3..5bc68c4ca5 100644
--- a/src/libslic3r/LayerRegion.cpp
+++ b/src/libslic3r/LayerRegion.cpp
@@ -1101,7 +1101,7 @@ void LayerRegion::simplify_entity_collection(ExtrusionEntityCollection* entity_c
 
 void LayerRegion::simplify_path(ExtrusionPath* path)
 {
-    const auto print_config = this->layer()->object()->print()->config();
+    const auto &print_config = this->layer()->object()->print()->config();
     const bool spiral_mode = print_config.spiral_mode;
     const bool enable_arc_fitting = print_config.enable_arc_fitting;
     const auto scaled_resolution = scaled<double>(print_config.resolution.value);
@@ -1119,7 +1119,7 @@ void LayerRegion::simplify_path(ExtrusionPath* path)
 
 void LayerRegion::simplify_multi_path(ExtrusionMultiPath* multipath)
 {
-    const auto print_config = this->layer()->object()->print()->config();
+    const auto &print_config = this->layer()->object()->print()->config();
     const bool spiral_mode = print_config.spiral_mode;
     const bool enable_arc_fitting = print_config.enable_arc_fitting;
     const auto scaled_resolution = scaled<double>(print_config.resolution.value);
@@ -1139,7 +1139,7 @@ void LayerRegion::simplify_multi_path(ExtrusionMultiPath* multipath)
 
 void LayerRegion::simplify_loop(ExtrusionLoop* loop)
 {
-    const auto print_config = this->layer()->object()->print()->config();
+    const auto &print_config = this->layer()->object()->print()->config();
     const bool spiral_mode = print_config.spiral_mode;
     const bool enable_arc_fitting = print_config.enable_arc_fitting;
     const auto scaled_resolution = scaled<double>(print_config.resolution.value);
diff --git a/src/libslic3r/Support/TreeSupport.cpp b/src/libslic3r/Support/TreeSupport.cpp
index 26838de593..a92b3196cc 100644
--- a/src/libslic3r/Support/TreeSupport.cpp
+++ b/src/libslic3r/Support/TreeSupport.cpp
@@ -1944,7 +1944,7 @@ Polygons TreeSupport::get_trim_support_regions(
     static const double no_overlap_xy_gap = 0.2f;
     double gap_xy_scaled = scale_(gap_xy);
     SupportLayer& support_layer = *support_layer_ptr;
-    auto m_print_config = object.print()->config();
+    const PrintConfig& print_config = object.print()->config();
 
     size_t idx_object_layer_overlapping = size_t(-1);
 
@@ -1991,7 +1991,7 @@ Polygons TreeSupport::get_trim_support_regions(
             const Layer& object_layer = *object.layers()[i];
             bool some_region_overlaps = false;
             for (LayerRegion* region : object_layer.regions()) {
-                coordf_t bridging_height = region->region().bridging_height_avg(m_print_config);
+                coordf_t bridging_height = region->region().bridging_height_avg(print_config);
                 if (object_layer.print_z - bridging_height > support_layer.print_z + gap_extra_above - EPSILON)
                     break;
                 some_region_overlaps = true;