Can you cite any sources for that claim? I found this blog post that says wayland is pretty much on par with X11 except for XWayland, which should be considered a band-aid only anyways: https://davidjusto.com/articles/m2p-latency/

Here's one article: https://mort.coffee/home/wayland-input-latency/

It's specifically about cursor lag, but I think that's because it's more difficult to experimentally measure app rendering latency.