I recently did some performance and latency testing between Gnome and KDE on Wayland
Results: https://drive.google.com/drive/folders/1xw0YtHGw6cQ2et8TKwlPXXE0FoA2V9hL?usp=drive_link
TLDR: they trade blows for performance, but KDE has a decent lead in the latency department. ( lower latency)