1.8 snapshots after 14w02a incredibly laggy

I find that when I try to use snapshots after 14w02a, the instant I go into 'more world options', the game suddenly drops in frame rate massively. Also, when I load any world, it lags enormously. It is really annoying as I want to use the new snapshots but I cannot due to lag. Literally, I cannot do anything without minecraft looking like a slide show, not a smooth game.