Investigate using multiple threads on BasicCompositor to improve full screen youtube video playback performance.

Snip from irc. <lsalzman> for very high res stuff, sometimes multi-threading/blocking can be a win <jrmuizel> lsalzman: yeah, that's probably worth looking into <jrmuizel> it's certainly worth experimenting with splitting the process into two threads to see how much of a speedup we can get there

So an easy way to try this out might be to replace the cairo compositing path with a pixman path. Then we could probably reuse Nical's infrastructure in gfx/2d/JobScheduler to do one half of the compositing on a separate thread.

(In reply to Jeff Muizelaar [:jrmuizel] from comment #2) > So an easy way to try this out might be to replace the cairo compositing > path with a pixman path. :jrmuizel, does it mean to create DrawTarget for pixman for compositing?