I upgraded to the 4 from the 3Gs a couple of months ago and I've noticed that everything seems to be slower on the iPhone 4. For example: 1. When I answer a call, it takes a lot longer to open up the screen that will allow me to click "speaker." 2. When I switch between things like email and texts it is really slow to open that screen. 3. I've seen some lag while inputting text for emails and text messages. The phone is not jailbroken and it's a 16G. I only have 3G available memory left. Could that be the issue? Any ideas?