It kinda stays on these levels, although now the framerate is at around 55 fps. I think that having one download happening was enough to stress my cpu and hdd enough
Yep, your content is HDR10. Tone mapping HDR content uses a lot more of your iGPU than regular transcoding. Regular transcoding just uses the Quick Sync portion of your iGPU. But tone mapping also uses the actual GPU via OpenCL.
Even on a dedicated graphics card, tone mapping is SIGNIFICANTLY slower than regular transcoding. The kind of FPS you are describing is normal for an iGPU tone mapping HDR content.
Jellyfin 10.10.3 (Docker)
Ubuntu 24.04 LTS
Intel i3 12100
Intel Arc A380
OS drive - SK Hynix P41 1TB
Storage
3x WD Red Pro 6TB CMR in RAIDZ1 (JF Library)
It kinda stays on these levels, although now the framerate is at around 55 fps. I think that having one download happening was enough to stress my cpu and hdd enough
This is more or less the same as mine and I am on i5-8500T. I can do up to 4-5 4k hvec transcodes though unless clients start to skip parts of the video then it will be laggy a bit but if no video skipping happening works just fine up to 5 client transcodes