This might be related to the issue I'm having http://www.nvnews.net/vbulletin/showthread.php?t=94480
Turning off renderaccel so far seems to have worked, and it seemed to be caused by suspending, or switching to compiz than back to metacity...but it's hard to tell. It definitely does slow to a crawl though.
I have a Thinkpad t61.
It really is bad, though. It got to the point where I was watching text being drawn on the screen, from top to bottom.