I have a second computer with an RTX 4090 for gaming (running Windows). I also used the new RTX 5090 running Linux to evaluate whether Proton/Wine allow me to run Windows games on linux (yes, it works, but the compatibility and frame rate issues make me stick to native Windows for now).
I wonder what's going wrong there? Personally I found compatibility and performance on Linux to be extremely good. And just keeps getting better. And that's not even just me, that's all kinds of benchmarks out there. Sorry to hear that. : ' (
If you want a GPU that has comparable performance on Linux to Windows- you want AMD. NVIDIA drivers are notoriously bad. Many of my games run better on Linux with the open source AMd drivers. (CachyOS rolling rolling rolling).