Stewmania

I don't know whats wrong when I play in the overworld there is no lag what so ever but when i go to a different dimension like the Nether it will start skipping like I'll be walking and it will pause then let me go again. And it will keep doing that, then when I go back through the Nether portal it will be even worse. I know that if i close down the game and start it back up it will be fine but if i go to another dimension it will start lagging again.