> Performance is perfectly smooth for me even with the AA hack above on Windows.

Playing with it more, my performance complaints appear to actually be caused by individual elements losing my mouse when I am clicked down on them and then drag outside of their bounds. This makes it seem like I have to keep re-grabbing things, the end effect is a lot of stuttering as I release and reclick on an element to grab a hold of it ahead.

Purely perceptual, but still nasty.