On my HT machine it uses 100% of the CPU in Task Manager (as opposed to 50% in all previous poser versions) and you see it rendering to different areas of the image at a time.  HOWEVER, towards the end it drops back down to 50% for some reason and basically kills any advantage.  I have timed renders with 2 and 4 threads (and also as a separate process) and the render times are IDENTICAL.  :(  

Actually, having in a seperate thread makes it a tad slower.

-Tim