Help Weird slowdown?

[Killerz187]

Occasionally I get this strange slowdown, where the screen is very slow to rotate, the messaging app takes ages to record my keystrokes, and it takes a bit to flip through the screens.

I'm still on the stock OS. Anyone else have this problem?

 

[Rockinfigs]

try restarting phone..should help

 

[Killerz187]

Restarting it fixes it, but I'm more concerned with what causes it in the first place.