It's not a huge amount of latency, so it's probably not super noticible to people who don't pay much attention. I'm pretty sensitive to input lag, and it does feel noticeably worse than both X11 without compositing and windows.

It is possible to get decent latency currently, with VRR + mailbox + fps cap, but there is still no VRR support if you use gnome.

I play a lot of FPS and third-person games so input latency is incredibly important to me. Honestly, once you try gaming in a truly low-latency environment (VRR, high refresh rate), it's hard to go back. Every time I try gaming in KDE Wayland on Radeon 680M, I notice mouse input lag and bad frame pacing.

The only Wayland compositor that I know of that doesn't exhibit these issues is the one used on the Steam Deck, but I am guessing there's some special sauce there.

Same boat as UrbenLegend, it's noticeable when playing FPS's. It's like the latency you experience when playing on modern game consoles, if you don't notice it, then that's great for you, but oncenyou get used to the low latency responses of PC gaming, it's really hard to go back, not so much for how it impacts how well you do, but because the latency suddenly feels like you lack control.

It really depends on the hardware. With 144Hz vsync isn't much of an issue for me, but 60Hz is noticeably worse with vsync on.

Most likely FPS games but probably any kind of game where you need a fast response time. I understand that some people don't notice input lag with vsync on, but for me it's unusable. I'm not even close to the "Top 1% Counter Strike pros" but when I'm playing Portal 2, CrossCode, Deep Rock Galactic, Valheim, CS Go, Path of Exile, etc, it bothers me A LOT.