I am using the YouTube app that comes with my phone. It is REALLY lagging on my 4S. I am over WiFi sitting right next to the router! Only YouTube is having this problem. Other videos like off the internet browser or Vevo work fine. There are no YouTube problems on my iPad 3 or my iPod Touch 2 over WiFi. (The iPad and iTouch are over the same WiFi as the iPhone.) What should I do to fix the lagging on my iPhone 4S's YouTube?