Slow scrolling, actionmenu flashes and bounces around when scrolling, Linux w/ Firefox3

This is the same problem as XSTOUCAN-9.
I was able to solve the bouncing flashing menu bar by removing all instances of "overflow" and "overflow-x" from the css (with firebug), scrolling still lagged a bit when the menu bar passed over pictures, but it was much less offensive. Changing the menu bar to position:absolute makes scrolling perfect.
This seems to be mostly a gecko issue, Opera has a slight lag on scrolling (with smooth scrolling turned on), but no bouncing flashing menu bar.