Comment 54 for bug 328232

@emms, yes it isn't a solution,it's a temporary solution, the bug is confirmed and no solutions until now, we can't work with a laptop that 1 process use 80 percent of it's cpu and as you mentioned for the memory, so at least, we have to act .

On the Ubuntu 9.04 release note, they mention that using UXA mode for Intel Video Driver will have a better performance. However, they also warn that UXA mode is experimental, so it could be very not stable.
to use the EXA mode you have first to downgrade your intel driver like i did
The way to rollback the original Ubuntu Intel video driver:
$ sudo apt-get install xserver-xorg-video-intel