Not sure how to say it, but i was referring to iPhones with their original version of iOS (eg. iPhone 3GS on iOS 3.0, iPhone 4 on iOS 4 and iPhone 4S on iOS 5) The question is: is it true that iPhones will always be the fastest (also mean best performance) on the original OS that it was shipped with? I always had this mentality that this is so. Then for some users, whenever they upgrade to a new iOS (eg, iOS 5 on iPhone 4), they may experience so lagginess and such. What do you guys think?