Expensive way to reduce loading times

[valle2000]

This might be a strange question but I'm not sure. I have been boxing for the last 2 years using the one install of WoW and just opening up 5 separate instances. It used to be slightly annoying to fill in details, but keyclone did this automatically for me and now with ISBoxer each character has a virtualised folder to store settings etc.

Is there any performance improvement available from having 5 separate WoW folders in fact? Interested in opinions.

You need multiple folders if you want to use different settings for each WoW instance (resolution, key bindings etc). Five may be "overkill" in many cases, but I personally want to know I can fine-tune each instance exactly the way I want.
But in most cases I think at least two folders are recommended. One were your master is launched since you may want to use higher graphic settings in that one. One folder where all your slave instances are launched since graphic can be set lower on those.

Edit: However, have never used ISBoxer so maybe you can do the same there?