So, you didn't notice that video playback in Firefox isn't hardware accelerated and stutters a lot? (Firefox' sandbox prevents itself from creating the OpenGL context needed for hardware accelerated video playback).
https://mastransky.wordpress.com/2020/06/03/firefox-on-fedor...
Also, enabled by default with Mesa in these days
https://linuxstoney.com/firefox-has-hardware-video-accelerat...
Wayland is a wip (a number of things are being worked on right now that have never even been fathomed for x11) and it's already a significantly better experience in countless ways over x11.