The Mac has no problem using sticky keys. ((NVidia GTX 675MX - 1024mb))
The PC Desktop - has very laggy tools when active under a sticky key. The only way around this is to toggle off all panels (~key). Although the Tools panel can be left on. ((NVidia 750 ti - 2048mb))
The Surface Pro 3 - Has the exact same behavior as the desktop when using an external keyboard. However, using the on-screen shortcut bar (Tablet Pro), there is no lag. Works as well as the Mac version. ((Intel gpu of some kind?))
This does not occur if you only have a few shapes in your scene. But import any of the AS11 sample characters (like the dragon), and you should see the lag. Makes no difference if you remove the bone layer from the characters.
If you haven't used the sticky key feature, this probably doesn't seem like a big deal at all. Once you get used to them, it's hard to go back though
