diff --git a/intern/cycles/scene/osl.cpp b/intern/cycles/scene/osl.cpp
index 5bc5fe58cba..0364393f7fd 100644
--- a/intern/cycles/scene/osl.cpp
+++ b/intern/cycles/scene/osl.cpp
@@ -48,7 +48,7 @@ map<int, unique_ptr<OSL::ShadingSystem>> OSLShaderManager::ss_shared;
 int OSLShaderManager::ss_shared_users = 0;
 thread_mutex OSLShaderManager::ss_shared_mutex;
 
-int OSLCompiler::texture_shared_unique_id = 0;
+std::atomic<int> OSLCompiler::texture_shared_unique_id = 0;
 
 /* Shader Manager */
 
diff --git a/intern/cycles/scene/osl.h b/intern/cycles/scene/osl.h
index bf6d260f292..ba4e88fbaac 100644
--- a/intern/cycles/scene/osl.h
+++ b/intern/cycles/scene/osl.h
@@ -4,6 +4,8 @@
 
 #pragma once
 
+#include <atomic>
+
 #include "util/array.h"
 #include "util/set.h"
 #include "util/string.h"
@@ -180,7 +182,7 @@ class OSLCompiler {
   ShaderType current_type;
   Shader *current_shader;
 
-  static int texture_shared_unique_id;
+  static std::atomic<int> texture_shared_unique_id;
 };
 
 CCL_NAMESPACE_END
diff --git a/source/blender/editors/grease_pencil/intern/grease_pencil_edit.cc b/source/blender/editors/grease_pencil/intern/grease_pencil_edit.cc
index 1e911cb5798..e00b1387c5e 100644
--- a/source/blender/editors/grease_pencil/intern/grease_pencil_edit.cc
+++ b/source/blender/editors/grease_pencil/intern/grease_pencil_edit.cc
@@ -2985,6 +2985,7 @@ static bke::CurvesGeometry extrude_grease_pencil_curves(const bke::CurvesGeometr
   const int new_curves_num = dst_to_src_curves.size();
 
   bke::CurvesGeometry dst(new_points_num, new_curves_num);
+  BKE_defgroup_copy_list(&dst.vertex_group_names, &src.vertex_group_names);
 
   /* Setup curve offsets, based on the number of points in each curve. */
   MutableSpan<int> new_curve_offsets = dst.offsets_for_write();
diff --git a/source/blender/editors/sculpt_paint/grease_pencil_interpolate.cc b/source/blender/editors/sculpt_paint/grease_pencil_interpolate.cc
index cf42d03e154..4d0b2bb2a33 100644
--- a/source/blender/editors/sculpt_paint/grease_pencil_interpolate.cc
+++ b/source/blender/editors/sculpt_paint/grease_pencil_interpolate.cc
@@ -455,6 +455,61 @@ static bool compute_auto_flip(const Span<float3> from_positions, const Span<floa
   return math::dot(from_last - from_first, to_last - to_first) < 0.0f;
 }
 
+static void assign_samples_to_segments(const int num_dst_points,
+                                       const Span<float3> src_positions,
+                                       const bool cyclic,
+                                       MutableSpan<int> dst_sample_offsets)
+{
+  const IndexRange src_points = src_positions.index_range();
+  /* Extra segment at the end for cyclic curves. */
+  const int num_src_segments = src_points.size() - 1 + cyclic;
+  const int num_free_samples = num_dst_points - num_src_segments;
+  BLI_assert(dst_sample_offsets.size() == num_src_segments + 1);
+
+  Array<float> segment_lengths(num_src_segments + 1);
+  segment_lengths[0] = 0.0f;
+  for (const int i : src_points.drop_front(1)) {
+    segment_lengths[i] = segment_lengths[i - 1] + math::distance(src_positions[src_points[i - 1]],
+                                                                 src_positions[src_points[i]]);
+  }
+  if (cyclic) {
+    const int i = src_points.size();
+    segment_lengths[i] = segment_lengths[i - 1] + math::distance(src_positions[src_points[i - 1]],
+                                                                 src_positions[src_points[0]]);
+  }
+  const float total_length = segment_lengths.last();
+
+  constexpr float length_epsilon = 1e-4f;
+  if (total_length > length_epsilon) {
+    /* Factor for computing the fraction of remaining samples in a segment. */
+    const float length_to_free_sample_count = math::safe_divide(float(num_free_samples),
+                                                                total_length);
+    int samples_start = 0;
+    for (const int segment : IndexRange(num_src_segments)) {
+      const int free_samples_start = math::round(segment_lengths[segment] *
+                                                 length_to_free_sample_count);
+      const int free_samples_end = math::round(segment_lengths[segment + 1] *
+                                               length_to_free_sample_count);
+      dst_sample_offsets[segment] = samples_start;
+      samples_start += 1 + free_samples_end - free_samples_start;
+    }
+  }
+  else {
+    /* If source segment lengths are zero use uniform mapping by index as fallback. */
+    const float index_to_free_sample_count = math::safe_divide(float(num_free_samples),
+                                                               float(num_src_segments));
+    int samples_start = 0;
+    for (const int segment : IndexRange(num_src_segments)) {
+      dst_sample_offsets[segment] = samples_start;
+      const int free_samples_start = math::round(segment * index_to_free_sample_count);
+      const int free_samples_end = math::round((segment + 1) * index_to_free_sample_count);
+      samples_start += 1 + free_samples_end - free_samples_start;
+    }
+  }
+  /* This also assigns any remaining samples in case of rounding error. */
+  dst_sample_offsets.last() = num_dst_points;
+}
+
 /**
  * Copy existing sample positions and insert new samples in between to reach the final count.
  */
@@ -471,38 +526,19 @@ static void sample_curve_padded(const bke::CurvesGeometry &curves,
   const int num_src_segments = src_points.size() - 1 + cyclic;
   /* There should be at least one source point for every output sample. */
   BLI_assert(num_dst_points >= num_src_segments);
-  const Span<float3> src_positions = curves.positions();
   if (src_points.is_empty()) {
     return;
   }
 
-  Array<float> segment_lengths(num_src_segments + 1);
-  segment_lengths[0] = 0.0f;
-  for (const int i : src_points.index_range().drop_front(1)) {
-    segment_lengths[i] = segment_lengths[i - 1] + math::distance(src_positions[src_points[i - 1]],
-                                                                 src_positions[src_points[i]]);
-  }
-  if (cyclic) {
-    const int i = src_points.size();
-    segment_lengths[i] = segment_lengths[i - 1] + math::distance(src_positions[src_points[i - 1]],
-                                                                 src_positions[src_points[0]]);
-  }
-  const float total_length = segment_lengths.last();
-  const int num_free_samples = num_dst_points - num_src_segments;
-  /* Factor for computing the fraction of remaining samples in a segment. */
-  const float length_to_free_sample_count = math::safe_divide(float(num_free_samples),
-                                                              total_length);
+  /* First destination point in each source segment. */
+  Array<int> dst_sample_offsets(num_src_segments + 1);
+  assign_samples_to_segments(
+      num_dst_points, curves.positions().slice(src_points), cyclic, dst_sample_offsets);
 
-  int samples_start = 0;
+  OffsetIndices dst_samples_by_src_segment = OffsetIndices<int>(dst_sample_offsets);
   for (const int segment : IndexRange(num_src_segments)) {
-    const int free_samples_start = math::round(segment_lengths[segment] *
-                                               length_to_free_sample_count);
-    const int free_samples_end = math::round(segment_lengths[segment + 1] *
-                                             length_to_free_sample_count);
-    const IndexRange samples = IndexRange::from_begin_size(
-        samples_start, 1 + free_samples_end - free_samples_start);
+    const IndexRange samples = dst_samples_by_src_segment[segment];
     BLI_assert(samples.size() >= 1);
-    samples_start = samples.one_after_last();
 
     const int point_index = segment < src_points.size() ? segment : 0;
     r_segment_indices.slice(samples).fill(point_index);
@@ -520,7 +556,6 @@ static void sample_curve_padded(const bke::CurvesGeometry &curves,
     r_segment_indices.last() = src_points.size() - 1;
     r_factors.last() = 0.0f;
   }
-  BLI_assert(samples_start == num_dst_points);
 }
 
 static bke::CurvesGeometry interpolate_between_curves(const GreasePencil &grease_pencil,
diff --git a/source/blender/render/hydra/final_engine.cc b/source/blender/render/hydra/final_engine.cc
index 14c92a4bc35..41579495daf 100644
--- a/source/blender/render/hydra/final_engine.cc
+++ b/source/blender/render/hydra/final_engine.cc
@@ -70,13 +70,14 @@ void FinalEngine::render()
   render_task_delegate_->bind();
 
   auto t = tasks();
-  engine_->Execute(render_index_.get(), &t);
 
   char elapsed_time[32];
   double time_begin = BLI_time_now_seconds();
   float percent_done = 0.0;
 
   while (true) {
+    engine_->Execute(render_index_.get(), &t);
+
     if (RE_engine_test_break(bl_engine_)) {
       break;
     }