So far, refactoring has been done.

@@ -31,10 +31,13 @@ struct bSound;
 #ifdef __cplusplus
 namespace blender::seq {
 struct MediaPresence;
+struct AnimManager;

@@ -0,0 +308,4 @@
+    for (int i : range) {
+      Sequence *seq = strips[i];
+      ShareableAnim &sh_anim = this->cache_entry_get(scene, seq);
+      sh_anim.mutex->lock();

@@ -0,0 +1,74 @@
+/* SPDX-FileCopyrightText: 2024 Blender Authors

@@ -0,0 +21,4 @@
+ public:
+  blender::Vector<ImBufAnim *> anims; /* Ordered by view_id. */
+  blender::Set<Sequence *> users;
+  std::unique_ptr<std::mutex> mutex = std::make_unique<std::mutex>();

@@ -0,0 +24,4 @@
+  std::unique_ptr<std::mutex> mutex = std::make_unique<std::mutex>();
+
+  void release_from_strip(Sequence *seq);
+  void release_from_all_strips(void);

@@ -0,0 +42,4 @@
+  /**
+   * Load anims used by strips and lock them so they won't be freed.
+   */
+  void strip_anims_acquire(const Scene *scene, blender::Vector<Sequence *> strips);

@@ -0,0 +52,4 @@
+  /**
+   * Get anims used by `seq`.
+   */
+  blender::Vector<ImBufAnim *> &strip_anims_get(const Scene *scene, const Sequence *seq);

@@ -0,0 +173,4 @@
+  }
+
+  if (is_multiview(scene, seq)) {
+    blender::Vector<ImBufAnim *> new_anims = multiview_anims_get(

@@ -0,0 +187,4 @@
+    }
+  }
+
+  for (int i = 0; i < this->anims.size(); i++) {

@@ -0,0 +222,4 @@
+    return false;
+  });
+
+  blender::Vector<Sequence *> strips_sorted = strips.as_span();

@@ -0,0 +305,4 @@
+  strips = remove_duplicates_for_parallel_load(scene, strips);
+
+  threading::parallel_for(strips.index_range(), 1, [&](const IndexRange range) {
+    for (int i : range) {

@@ -0,0 +310,4 @@
+      ShareableAnim &sh_anim = this->cache_entry_get(scene, seq);
+      sh_anim.mutex->lock();
+
+      sh_anim.acquire_anims(scene, seq);

@@ -372,0 +378,4 @@
+  AnimManager *manager = seq_anim_manager_ensure(SEQ_editing_get(scene));
+  manager->strip_anims_acquire(scene, seq);
+  blender::Vector<ImBufAnim *> anims = manager->strip_anims_get(scene, seq);
+  int count = anims.size();

@@ -1239,1 +1248,3 @@
-                             BLI_listbase_count_at_most(&seq->anims, totfiles + 1) == totfiles;
+                             std::min(anim_count, totfiles + 1) == totfiles;
+
+  if (anims.size() == 0) {