Minecraft 13w21a is super laggie on a laptop

When you start playing in your minecraft world(s) and if you are playing on a laptop the game will be extremely laggie even if you turn all your settings all the way down you will be barely able to even Control your character due to the insane amounts of lag, please fix this bug please this bug is really starting to get to me and I'm sure everyone else who plays on a laptop HATES this bug as much as I DO.