I have been knocking Ubuntu and big distro's for extremely slow screen response and lag compared to windows. I know many, many people on forums are thinking the same thing - Linux has bad response compared to Win.
Then I bought a new laptop with Intel video, and despite being half the spec of my main Linux workstation PC, the laptops Gnome session runs as fast as Windows. Then I purchased another PC with Ati video card, and that too was as fast as Windows e.g. instant response from moving windows and scrolling Nautilus/Browsers etc. Only the first PC, with NVidia video card, has terrible response (although the infamous Placement=2 line gets me a touch closer to the speed I'd expect).
Then I stumbled upon the Nvnews forums and learnt that my 8600GT video card is effectively a three legged horse in Linux due some mysterious problem with the drivers/x-rendering.
Anything beyond 6 series Nvidia cards have worse Linux 2d performance than the cheapest Intel/ATI card. Even top of the range 8800GT etc...
I just kitted out a new business with 8 new machines and made sure none of the machines have NVidia video technology.
I am posting this message on Ubuntu forums to warn others. NVidia absolutely must get this sorted but from what I can gather havent even made an official comment to acknowledge the problem.
See NVIDIA FORUMS AT:
http://www.nvnews.net/vbulletin/forumdisplay.php?f=14
I have no involvement with Ati, Intel or Nvidia beyond wasting £100 buying a 8600GT recently believing it would be the best choice for Linux.