On the whole, application launches are an average of 15% slower on the iPhone 3G running iOS 4.1 than iOS 3.1.3, down from nearly 44% on iOS 4.0.1.
Some measurements from Anandtech proves, how fucked up the iOS 4 on 3G is, but misses some part of the problem, too. The iOS 4 is not only horrible in app launches but the general feel is sloooooowwwwww.
Apple has really screwed up the kernel for older devices and fixes it only partially. I don’t give a fuck about new features, just gimme (and 30M other people) what I got before