I wonder if you are actually seeing a CPU bottleneck or something else, like little-to-no GPU acceleration.

Photoshop 3D performance is better on Windows than on OS X. And trying to do 3D on an Intel IGP is a lost cause, even with Ivy Bridge. When you run Photoshop on a Windows desktop all the 3D rendering is done on the video card.

When I say people use MacBook Pro's instead of Mac Pros I'm not talking about the 13". It's exclusively the 15". The only person in my office with a 13" is actually me, because I bring my own machine.