How many processors dose your Mac have. If it's a G4 there is a good chance that you may upgrade it to a dual processor deal cutting your render time considerably. I have a dual 1.2 and it dose render reasonably fast compared to the G3 I used to have. Carrara is written to use two processors if you are using OS X. Depending on what model you have, I believe that their are several 3rd party solutions out there for you to choose from.