I've been dealing with a slow 3G ever since I downloaded 4.0. There may be a select few whose 3G works fine after the upgrade, however, the majority of us are dealing with 5-8 seconds of waiting for Settings to open, seconds for the screen to flip, foreve until the keyboard pops up, slow reaction when typing.. Etc.. 4.0 was just not designed for th 3G. So, after reading many forums and seeing that this is, truly, and issue that Apple hasn't resolved nor admitted to agreeing that indeed it is slow, the only solution is to downgrade back to 3.1. Lifehacker has a very easy way of doing this. I did it last night and I'm finally happy with my phone again. Everything is back to instant! Rebooting, turning things off.. All that won't make your phone faster.. Downgrading will. At leas until Apple releases a 3G friendly version.