I find this hard to believe. Generally speaking, games run slightly slower on Linux (that's on Arch with latest Nvidia drivers). Usually, the difference isn't really noticeable, and several rigorous benchmark show that even though average FPS is single digits lower, the standard deviation is also smaller. This may be due to Nvidia not performing as well on Linux, the worst impact I have seen is on Helldivers 2 (at least 15 to 20% lower FPS).