Comment 30 for bug 798868

Hard to tell if it's the same effect as in original posting, but the description of Reid Kaufman, Nate Wiebe fits best.

Good and smooth desktop performance only moving windows around is like slow-mo. Windows lagging behind mouse cursor when being moved about 1-2 seconds (resizing as well) - smooth non flickering, but way too slow.

I installed a fresh oneiric ubuntu 11.10 on my netbook Samsung NC10 with intel graphic (OK, no probs) and on my desktop with onboard nVidia 8300 (slow window movement here!).

Out of frustration after "nvidia-current" and "current with updates" and most recent from nvidia website in combination with vsync on/off, tripplebuffer tricks a.s.o. didn't work I finally switched both machines to Lubuntu 11.10. Everything OK on both machines because no compositing on desktop by default.

As I wanted some eyecandy I installed xcompmgr on both machines with just shadows attached to my windows: the effect is back on my nvidia-machine just like on ubuntu/unity!

So I suppose it's not unity but nvidia + compositing (+ current xorg-version-of ubuntu?)

I have no idea where to search nor what to post to help to find a solution to this.