Comment 13 for bug 599425

I disabled the launcher entirely and still managed to get Mutter's CPU usage to 13% with mouse-over on the area the launcher would be, which seems to indicate that all this is tied to the input region.

I therefore disabled the in put region (while the panel and launcher still painted/updated through their models) and boom, CPU usage never spilkes above 3%.

So, it seems that there is some foul-play happening between the painting during mouse-events in the input region of mutter compared to the when the mouse is moving in the region of the screen where mutter is not receiving events (and therefore only processing some launcher/panel events, but mostly texture-from-pixmap events through X). This is why we can make mouse-movements on the panel (which has *no* roll over states) spike CPU to 10%. it's obviously causing a paint for no reason.

Will look in more depth at this tomorrow (although please still provide your results).