7970M - bad performance in Mirror's Edge

So I picked up Mirror's Edge on the Steam Sale knowing that it's a great game (so far, so good!) and at $5 its a total steal [i.e. go get it! except if you have a 7970M.... read on].

I enjoyed playing the game (absolutely beautiful for it's time) with everything maxed out (for some reason it caps and stays at 62.1fps, but whatever, that's what Afterburner's OSD is telling me) however, in the second mission where you *spoilers!!* find out your sister has been framed, and you have to escape from the cops (?) well with all the shooting and breaking glass, performance dips to below 10fps and is naturally unplayable.

I'm guessing Physx is the culprit here since I'm running an ATI card, but does anyone know how to fix this; as in, turn Physx off? The game runs fluidly aside from those shooting scenes, and I definitely don't want to dial down settings just for that when the game itself runs like a breeze otherwise.

Any thoughts, anyone? Would really appreciate feedback. Hope you're enjoying the awesome Steam Sales btw

EDIT: Oh, and the game crashes, every time, later on during that same mission. Tried with an OC of 900/1400, 965/1460 as well as stock. No difference in performance at all. I will be in *utter disbelief* if I'm told the 7970M is "uncapable" of running this game lol

EDIT #2: Yup, turning PhysX off helps fix that (silly me for not turning it off), but what disappoints me is that the 7970M performs so badly on an old game when even BF3 runs fine on this.

 

There will always be games and hardware that dont match. PhysX seems to be dying off (at least I hear far less of it) and I think AMD is not testing PhysX compatibility anymore. Maybe the version of PhysX is also the culprit, as even games like Dragon Age forced a PhysX on me and if it wasnt the right version, it would still complain.