There is a promising new hair plugin for C4D, made by Renato Tarabella. It's called Fast Fur.

You can find it here :

http://www.tarabella.it/c4dbeta/index.php

Rendering time is drastically decreased. It took me only up to 7 minutes for the most complex of these pictures with only one CPU (Athlon 2.8) and 1,5 Go of Ram.

Enjoy,
ivan