What quality settings are you looking for? Even
at launch, the GTX 750 Ti wasn't a 60FPS card at 1080p, high quality presets. It might get there at say 1440x900 or 720p at the same quality settings.
With regards to PhysX, most games that use it expect the CPU to handle it. I'm not sure if at that point the CPU still handles it or gets shipped off to the GPU, but even in the latter's case, there would be little to no performance impact. For games that enable extra effects when using PhysX, the performance drop depends on the game. Some games can drop performance by 40-50% on then midrange hardware, others by 10-20%.