I use both OS X and Ubuntu. In comparison, Ubuntu is terribly slow, even on basic things such as dragging and resizing windows, let alone graphically-intense applications. This is both with ATI's proprietary drivers and the opensource radeon driver. Things are a bit better if I don't use a compositing window manager.

I am not sure who is to blame, X or the drivers. But most users won't care. They'll see that GNU/Linux has a bad desktop experience, and revert to whatever they were using.

I'm using Intel hardware on a large display, and of course Intel makes all the information available to driver writers and the X drivers are open source and very high quality. And there is no lag. I used to use Mac OS X before and there's no difference.

So this sample of two users seems to indicate that your problem is with drivers. Wayland will make no difference to your experience of Ubuntu.

Please try bodhilinux with enlightenment as window manager and you'll see that gnome/unity are slow, not X.