I've done a test scene, a toon scene with an roman arena, 2 gladiators and some public and soldiers, 13 figures in total.

 

1 thread: 3min17secs

2 threads: 2min11secs

3 threads: 1min51secs

4 threads: 1min41secs

 

As you can see from the numbers, the extra threads to make a difference, if they're not used in rendering, they're kept free for other stuff and influence the preformance.

With the test scene BB pointed to, 2 thread render the scene in 59secs and 4 threads in 45secs. More threads do make a difference.

Artwork and 3DToons items, create the perfect place for you toon and other figures!

http://www.renderosity.com/mod/bcs/index.php?vendor=23722

Due to the childish TOS changes, I'm not allowed to link to my other products outside of Rendo anymore :(

Food for thought.....
https://www.youtube.com/watch?v=pYZw0dfLmLk