I've noticed throughout the years with my iPhones and iPads, that every update seems to slow the OS . When you first purchase an iPhone or iPad, they are blazing fast and they never have any problems right? Then you update it throughout the years and they eventually become so slow that you "have" to buy a new one.
This is Apples way of "throttling" . Basically what this means is that they intentionally slow down the phone after every update so by the time they discontinue it, you are dying to buy the latest one.
For example the new iOS7.... slow as shit.
This is why I own an android now!!!