There's still room for improvement, but Linux gaming has come a long way in a short time.
I remember when Proton launched it was like magic playing games like Doom and Nier Automata straight from the Linux Steam client with excellent performance. I do not miss the days of having the Windows version of Steam installed separately.
Okay I can definitely back up the second claim.
World of Warships, a DirectX only game, runs and loads better on Linux with Proton.
I tested both on SSD and HDD, and in both scenarios the game runs at a higher FPS and loads faster. I legitimately have no idea why.
I originally tested on HDD and guessed that ext4 was just much better with the IO speeds because NTFS would fragment like hell.
But then it also was the same with an SSD and now I'm not sure.