I installed Kubuntu on a friend’s desktop, and they need Wayland because they use two displays at different scales. Unfortunately, Plasma on Wayland is extremely slow compared to X11. After login the desktop takes something like 15 seconds to load (less than 5 on X11), and when Plasma is called on to do something by a mouse input (make menu appear, select menu item, etc.) it similarly takes a really long time (5-10 seconds) for the result to materialize visually. There was no delay when it came to moving windows by dragging with the mouse.
They have an nvidia card (GTX 1060) and are using the proprietary nvidia drivers, which I suspect might be relevant.
I’ve tried to look for similar issues but haven’t found any exact matches. I was just wondering if someone might have some insight.