Have you checked whether this happens on Windows?
Wouldn't surprise me if the game just does a bunch of BVH updates that are slow on Windows too.
Works fine on Windows even on AMD. Maybe there are some driver workarounds made by AMD I dunno. Overall the RT is lightweight in this game (on Low-Mid RT without reflections) with almost zero FPS penalty. It looks the same on both there is just this performance difference.
I remember having this issue on the demo. I thought it was a Radv specific issue. Looks likes it's not.
This happens with any of the three RT settings. When the camera is still I have 80 FPS, then with slight movements in any direction or just moving it in circles it tanks to 15 FPS, especially when zoomed in. It's also noticeable in the later scenes in the game's built-in benchmark. Mesa 25.3.6, GE-Proton10-32, RX 7900 XTX, Fedora 43 with 6.18.12 CachyOS kernel.
I spent some time recently analysing this issue. It looks like it is CPU bound, I can see the spikes on Steam overlay CPU graph, especially when zooming in and out. The same issue is happening on Windows when I use the same vkd3d libs there. For me it is just happening in this game. I attached the profile dumps in the issue desc.
This issue no longer occurs I tested with GE-Proton11-6 https://github.com/GloriousEggroll/proton-ge-custom/releases/tag/GE-Proton11-6
There is stutter and frame drop that happens on camera movement. Feels like shader compilation but it never goes away even after reloading the game or longer playing session. It happens on both NVIDIA and AMD GPU.
Could be related to https://github.com/HansKristian-Work/vkd3d-proton/issues/2811
Software information
Anno 117 latest version on Steam, set to High 4k FSR4 Balanced, RT on Medium
System information
Log files
steam-3274580.log
UDPATE 01.04.2026
I noticed the same stutter in Resident Evil Requiem when RT is enabled.
EDIT 08.05.2026
I spent some time recently analysing this issue. It looks like it is CPU bound, I can see the spikes on Steam overlay CPU graph, especially when zooming in and out. The same issue is happening on Windows when I use the same vkd3d libs there. If I zoom in and out several times the same spot the stuttering eventually goes away. But it's back when I move the camera.
For me it is just happening in this game.
I built vkd3d-proton with profiling enabled and made some dumps with and without RT. Maybe this can be helpful
anno177_dump-.zip