Just want to share my learning as I struggled a lot with having suddenly fps like 10 to 15 in Valheim. Finally that was caused by switching HDR on in Win11. Somehow HDR messed the system and changing settings or any other hints in the Internet didn't help. So: HDR off, pc reboot and then Geforce Experience reconfigure... hopefully this helps someone struggling with the same problem. HDR works fine with other games, but I don't know if it can be excluded only from Valheim with some console command?