just to put this out there. If your friend is using a video card with shared video ram, that could account for the huge increase of ram, other then that I can assure you it's not a addon doing it. Unless they are all poorly written.
I suggest that if you are that deeply concerned about the ram issue that you run something that will show addon ram use.
this
http://www.wowinterface.com/download...ememfpsms.html
combined with a data broker will do that.