Sorry I spoke too soon, I was just in an area with better framerate. Timeslice shadows make no difference. I'm using Catalyst 10.11.

My new theory is that it's due to PhysX being supported horribly/not at all on ATI video cards (PhysX is an Nvidia thing). For example when I try to enable PhysX in Arkham Asylum the game turns into a slideshow. At least Arkham Asylum lets me disable PhysX! I can't find a way to do this in Divinity 2.

If anyone could tell us how to disable PhysX we might get to the bottom of this. Thanks,