This should help
I can't really provide comparative RAM figures because XP doesn't accurately report RAM usage.
As for times; The simple-ish scene I just rendered (my old wallpaper with my avatar and the flames) clocked in with a 2 second diff (with 11 winning) but 2 seconds is pretty negligible. Probably see an difference with more complex scenes, more specifically ones using the new render instances feature and the other improvements that mentioned on the link up the page. (But my computer isn't the same as yours so you might see more improved times)