I've got several 1080p movies encoded by Handbrake in H.265 12-bit format that are problematic to view in recent versions of VLC x64; lots of skipped frames, I'd say I'm getting about 2FPS. No excessive CPU or GPU usage.
PC spec:
AMD 7800X3D
32GB RAM
Win11 64 23H2
AMD 6700 XT (latest driver)
I've tested several x86 versions from 3.0.0 to 3.0.20 and none have this problem. I then followed up with testing x64 versions, starting with prefs/cache deletion:
x64 vlc 3.0.20 not ok
x64 vlc 3.0.0 ok
x64 vlc 3.0.10 not ok
x64 vlc 3.0.5 ok
x64 vlc 3.0.6 ok
x64 vlc 3.0.7.1 not ok
x64 vlc 3.0.7 not ok
VLC in Linux Mint 21.x has no problem with the clips; I assume I have the latest version but I can check when I reboot back into Linux.