I get my wife's hand me down phones, currently the 4. Anyone with a iPhone 4 seem to have a significant lag? For example, after pressing Messages icon, I can count up to 4-one thousand before the Messages screen pops up. Basically, it takes the apps 2-4 seconds now to open -- a 100-400% increase in lag. Once the apps are in the background memory, they do open up quickly. I hope the 4s does better since I will be getting that when my wife's 5s arrives.