I installed a fresh copy of Windows 11 on a new partition and all games except Diablo 2 and Northgard run at 10 to 30 FPS. Games I've checked are Apex Legends, Elder Scrolls Online, Valheim and No Man's Sky. I think the former run smoothly because they don't utilise much of the 3D capabilities available to render the game, while the other ones use 3D heavy engines like Unreal Engine and the lot. I've installed all the latest Windows and graphics card updates and drivers to no avail.
All games run smoothly on my other Windows 10 installation with FPS between 80 - 160 fps.
System CPU: I5 9700F RAM: 32 GBs GPU: Nvidia 2080ti Storage: SSD Motherboard: Asus PRIME H310-PLUS.