updated 12:50 pm EST, Mon November 8, 2010
Input lag substantially reduced
The iPhone 3G behaves much better under iOS 4.2 than previous v4.x releases, testing shows. Although v4.0 and v4.1 are technically compatible with the 3G, people have complained about lethargic performance not present with the earlier v3.x firmware. Apple has in fact been hit with a class action lawsuit accusing it of intentionally crippling the phone's performance in order to push people to the iPhone 4.
iOS 4.2 is described as comparatively fast on the 3G. While some aspects of using the device may still suffer from input lag, such as typing and web browsing, the problem is now far less severe than previously observed. It may in some cases be attributable more to the iPhone 3G's hardware, which is substantially slower than later iPhones, and equipped with a quarter the RAM of the iPhone 4.