Is that free update for the Steam version as well? Wondering if they fixed the broken Physx support (or better yet removed it completely).
The PhysX effects worked fine (and could be turned off if you wanted). They were a big hit to performance, sure, but that's the nature of the beast with Nvidia extensions.
The real problem with Borderlands 2 is that it's a CPU destroyer in certain areas. If they could optimise that, it would be a big deal.