I'm booting an iMac from an external hard drive. WoW is on that hard drive and I was wondering since WoW has a reputation of slowing down computers, if I play while on the external drive will it still degrade performance of the computer when it's booted off the internal hard drive? ANd if it does, how noticeable will it be? My email is firstname.lastname@example.org please email me if my question is unclear. THANK YOU!!!