It actually depends on several factors. Surprisingly, games that are heavily CPU bottlenecked often run better on Linux under Proton than the native Windows version.

That being said, for games that are GPU bound, a 20% deficit on a Nvidia GPU is actually about what I’d expect.

I’ve found that it depends heavily on what game you’re playing. I wouldn’t say 20% loss is uncommon.

You could try using a kernel tuned for gaming but it probably won’t make up the difference.

Honestly you’re probably better off not comparing to Windows. You’ll often fall short performance and feature wise.

Edit: I’ve also found that people tend to oversell Linux. We desperately want more users but exaggerations do more harm than good.

You should also mention which nvidia driver you’re running btw

Probably Nvidia is too blame. With where things are now I would probably want an AMD card for a dedicated Linux gaming machine.