Imported Video GPU Decode is Unoptimized and Painfully Slow in After Effects

[dandiw45248892]

Expected behavior: When rendering the preview of a comp that has an imported 4K h264 video, I expect that my computer wouldn't use 100% of the GPU Video Decode. When viewing the same 4K video in VLC, my GPU Video Decode is only about 13%.

Actual behavior: When rendering the preview of a comp that has a 4k imported h265 video, my GPU Video Decode jumps up to 100%, and the preview render is a fraction of real-time.

Why I think this is a bug:

1. This happens in a comp that has no other layers except the imported video, but the video plays back faster when just previewing the footage panel
2. It is a basic 4k medium bitrate Adobe Stock preview video that plays back without issue in VLC
3. The RTX 3090 GPU is plenty powerful and supports hardware decoding
4. After the imported video has decoded, all the green bar preview plays back without issue, so I know it has to do with the initial decode of the imported video
5. During this issue, CPU usage is very low, M2 SSD usage is about 0%, and memory usage is about 50% of 32gb

Is anyone else experiencing this? It's making basic work with imported 4k video very difficult.

[dandiw45248892]

Typo: the video is H264, not HVEC 265