Jailbroke my iPhone 4 5.1.1 for the first time yesterday. I've always been an overclock guy. I always seem to overclock all of my computers and phones. Thought I'd give ioverclock a try today and I can notice its a bit 'snappier' when loading and opening things which is what I wanted. It's definitely not a speed machine now but it is quicker because it takes off the under clock that apple applies to the processor so it runs at the true 1ghz instead of 800mhz. Obviously I can't test it to make sure unless there's an app to do so that I don't know about. But regardless, it feels quicker. Battery life might just slightly worse but nothing at all bad. And this app now doesn't mess with the sleep ability so it will let the processor rest and not kill the battery in an hour lol. Anyone who is interested should definitely try it. I'm happy with it.