I went to the T-Mobile store today to play with a Galaxy S3 on 4.1.1 Jelly Bean. I noticed the device was a bit laggy when moving through the OS. Nothing too bad, but it wasn't as responsive as the Nexus 4 next to it, or the iPhone 4S in my pocket. Just had a slight hiccup when moving between screens and sometimes touches didn't register. Why was the phone laggy, and is this something that can be fixed if I root the phone?