Does Wayland really break everything?

I think this is already fixed. Not sure if this is Plasma 6 only.

There is currently work being done improve KWin on weak hardware.
One is Tripplebuffering: Draft: backends/drm: allow having two frames in flight ("triple buffering") (!4833) · Merge requests · Plasma / KWin · GitLab
The other I forgot, but there is either a merge request or it is already merged.