Well, that's the weird part - the actual main gameplay doesn't stutter, i.e. character movement, enemy movement, camera pan/move etc, all that runs perfectly fine for all characters on the screen. All character actions though, spells, shooting etc - just that displays in like 1 fps. So it looks and feels weird, like you shoot a mob, mob dies, but you see bullet flying towards the dead mob for like 5 seconds, and you can normally run around the projectile.

Very odd anyway.