Tsk tsk, looks like this software is not multithreaded very well. Spinning around the PTC Academy / Aston Martin model using "enhanced Realism" brings my computer to its knees, takes a second or more to redraw the 1680x1050 screen as I spin the model around.
And what do I see on the Windows XP Task Manager? PTC is only using 25% of the system capability to do this, which means it is single-threaded.
Listen PTC, with multiple cores, assign 1/n of the display area to a core (4 cores = 1/4 th per core), and have them divide up the work. Checkerboard division of the screen (say, 100x100 pixel blocks) will deal with distribution of large blank/used render regions better across all cores.