I have an Xperia Arc but lately it's started to run like a dog. There's quite a lag between pressing the screen any anything happening, and apps seem to take a good 5+ seconds to open. Opening the camera takes even longer. I don't have that many apps and have no widgets running. Any advice? I've never rooted a phone - could that help? Not worried about warranty as it's a year old and this is kind of last chance saloon before I look for a new one. Thanks.