So, I want to throw my story into the fray. I've been 5-boxing for quite awhile now (ran a "pve" group Pr/Ma/Ma/Lock/Warr to lvl55 before I realized that I really wanted a PVP group, and now have 5 shamans to 56) and ever since I started I've used the 5 separate folders of WoW method. I always read that the performace was slighty better doing that, and that its easier to keep track of mods and such for clones.

Well, using this method I always MAJORLY lagged in IF and i could not use Boats as a method of transportation because the boat would be pulling away from the destination before my load screen would finish on all 5.

For shits and giggles this weekend, I was reading this thread and decided "Hey, maybe I'll try 5 WoWs from the same folder. A few changes in my keyclone command editor and I was up and running. Holy crap what a difference. Everything loads so much faster. Instances/zoning/boat rides/logging in/logging off/etc.

For now, I'll be sticking to this method.

Just my 2c.