Greetings, several of my friends have the iPhone 3G and 3GS and for some reason they run very slow at times ever since the firmware upgrade was made to 4.0. For example when typing a text or email ithe text may not display on the screen for 15 to 30 seconds. But sometimes there is no delay. Before the firmware upgrade this was not a problem. I have a iPhone 4 and don't have any problems like this at all. Any ideas on what is causing the 3G(s) problem and how to fix it?