Well, it seems the iPhone 3G hardware is not only inadequate to handle multitasking, background imagery and some other goodies offered in iOS 4, but certain users who took the plunge feel it simply can’t handle it,.. period. Issues have gone as bad as users not able to even use the software keyboard without significant lags. So hey, if you’re having the same problem, our opinion is it becomes worthless to upgrade if you end up with a slow phone at the expense of not getting the most important reason for the OS to exist (multitasking).
Over at Lifehacker they’ve figured out how to help you downgrade your device to the previous iOS 3.1.3 without the need of complicated hacks. Surely you won’t be carrying the newest form of iFun, but hey, at least it’ll iWork. Here’s the complete How To, which apparently works on both Windows and Mac OS.