Don't accidentally go off the screen when you've got a buddy. It gives you a "whoops" thought bubble then you're stuck off screen for forever, have to restart... No desire to pummel that many werewolves again.
I don't know what happened, but I played this yesterday for the easy badge then returned today for the hard. The first 25 levels went by with minimal lag. Today I'm struggling to finish a single level before memory consumption goes up to ~1GB and the game becomes unplayable due to lag.