Is it true that having four folders is worst than having the folders symlinked?

Also which folders should be symlinked to increase performance?

I just have four separate folders. I guess I could really go with 2 (one for the main and one for the slaves). I dont care about high graphics settings and addons for all the slaves, I barely look at those screens.

Thanks

P.S. Since 3.0 patches have come out - my computer has really sucked. It was amazing before the patch tho. I have another video card on order. I dont count on blizzard to fix the issues any time soon. When BC first came out it sucked for a while also.