I am running archlinux (xorg 1.8 and nvidia 256.35) and i noticed that X uses a lot of cpu when browsing pages with bug-lists on launchpad with firefox, e.g. :
Other archlinux users have reported the same when running nvidia but an ATI users did not see this behaviour, so this could be a nvidia driver problem.
It would be interesting to hear if people here can reproduce this.
nvidia devs, please tell me if you are interested in some X debug logs and how i can create them.