Keyboard and mouse input delays with Firefox on Wayland
I tried Firefox 86.0 on ArchLinux with a KDE Plasma (Wayland) session. All Qt and GTK applications function normally. Firefox does not crash, but there is a noticable delay while typing or interacting with the mouse. It seems the input is received but it is not rendered on the screen.
I used the profiler and uploaded a profiler session to help you investigate the problem.