The 3D function on my Photoshop CS 6 Extended is really slow and it is taking a long time to load the changes as well as show them to me in real time. (Intel Core i7-3630QM CPU @ 2.40GHz 2.40GHz, Installed memory(RAM) 32.0 GB(31.9 GB Usable), System type: 64-bit Operating System, x64-based processor[Windows 8],Video Card: 2GB GDDR5 NVIDIA GeForce GTX 680M) valid to say, only Photoshop and Bridge running.
With them specs, it shouldn't be very slow, unless you have a very detailed mesh loaded. Try resetting your preferences and see if that helps any.
To reset your prefs follow the directions in the video below: