If anything, it's slower. I expected 11.5 to be faster than 10.5, which it wasn't -- much much slower -- and 12 so far is even worse.
I found that often a final render was faster than Open GL rendering! Outrageous. (All this on a Mac G5 dual processor machine.)
And, A simple test I've done, has real strange errors in rendering. I drew a circle and rectangle, with some overlap, and extruded them. Filleted the edges. Chose a color. The color shows up in OpenGL rendering but it's gray in final. But in open GL the surfaces disappear, though they are there in final. Different rendering styles give different -- inconsistent -- results.
This is very depressing. Then again, the interface is different enough that it probably won't be all that bad to switch to Solidworks, which I am -- sadly -- thinking of doing. VW 12 is just too slow, and not really optimized for mechanical design.
Please fix it so I don't have to get a PC!