Attached Link: http://www.keindesign.de/stefan/poser/firefaq.html#1

SR3 helps with *subsequent* loading times within same OS session. (First one is slower than pre-SR3 in my experience.)

Removing Content Parasite helps with Poser load times (all), and with responsiveness of Parameter Dials esp. on some instances of Poser 5. (Save the old unedited file though, you may need to install SR4, or better just comment out the necessary lines.)

Correct Reference helps with load times of products with incorrect texture filenames (even if Poser can find them without asking you to).

Only help with rendering times is a minimum memory size (which depends on your scene complexity), raw CPU power, and/or by playing with the FireFly parameters. Check link above for info on the latter. (For the CPU/memory discussions, see http://www.renderosity.com/messages.ez?Form.ShowMessage=1418149 and follow the 3 links provided there.)