In both 4.0.3 and 4.1.0, the X server would spin using 100% of the CPU on my IBM ThinkPad 600 (NM 2160). Turning on Option "NoAccel" stopped this, but performance was unacceptable. None of the various "xaaNo*" options I found in the archives seemed to help.
Finally, I found that using Option "ShadowFB" works well. The man page for shadowfb(4) seems to be missing, so I have no idea why this works. (I guess it's the general principle that adding a layer of indirection can fix any problem :-) Hope this is useful to others. Eric [EMAIL PROTECTED]