Poser 13 requires less pixel samples to get the same quality of image.  If you use the exact same settings it won't be faster.  The thing is you need less to get the same image.  There is a point of diminishing returns where no matter what you do the image won't get any better.  At which point you are then just wasting time.

Poser 5, 6, 7, 8, Poser Pro 9 (2012), 10 (2014), 11, 12, 13