- ImBuf reference counting: turn that into just an atomic integer - Cachefile safety: turn into a mutex, since work under the spinlock was quite heavy (hashtable creation, other memory allocations) - Movie clip editor: turn into a mutex, since work under the spinlock was very heavy (reading files from disk, etc.) - Mesh intersect: remove the previously commented out spinlock path; replace BLI mutex with C++ mutex for shorter code Pull Request: https://projects.blender.org/blender/blender/pulls/137989