At 60 Hz, there are 16.6 ms between frames, so the ~3 ms improvement from not using XWayland would be very hard to notice visually. Where it can make a difference is that some competitive FPS games have some kind of client side hitscan or lag compensation and often play at high refresh rates, so there it can actually matter that their system reports to the multiplayer server that you clicked in the right place a couple of milliseconds earlier.