If I had to guess it's RADV compiling RT pipelines (which are pretty big in UE games) in the background. Improvements for compilation performance are in the works on the RADV side.
I can confirm the issue in "Lordsfell" in Immortals of aveum. Simply entering the location or staring at the stairs later on causes 80-90% cpu load on my 5950x and the fps tank down to ~ 25fps. Googling shows that the game is not using hardware rt, but lumen software rt. The issue is the same with radv and amdvlk. In addition the issue does not stop after some time.
This is likely a completely different issue, then.
https://gitlab.freedesktop.org/pixelcluster/mesa/-/commits/trav_separate_compilation_ra
This branch fixes the issue.
Merged in Mesa main with this
https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/39314
Issue can be closed.
proton experimentalx1 2024-01
There is very high CPU load at dense places like Hogwarts and Hogsmeade when traversing, e.g. ~90% load on 8C 16T. This is not normal, CPU load on Windows is more like half of it (i.e. poor UE4 MT). It doesn't occur with RT off. There is a similar issue in Immortals of Aveum (too in dense hubs with many NPCs). But not sure if related, as that one should be software-RT only.
Software information
Latest Hogwarts Legacy Steam version, maximum settings, RT reflections-only, RT ultra
System information
Log files
steam-990080.7z.zip