[kirstein]

If it's the screen sensitivity, you can go through the screen alignment process again. It sets the touch sensitivity based on how hard you touch it.
Go to settings>all settings>screen and run the alignment again, but just tap the screen as lightly as possible.

I've noticed the screen can also get laggy if it's doing a lot of stuff in the background, like updating push internet or stocks or weather. Try turning all that stuff off.

I