https://www.dropbox.com/s/anyukzkonv91ils/Screenshot%202015-03-15%2004.03.52.png?dl=0

https://github.com/iChun/Hats/blob/master/src/main/java/hats/client/core/TickHandlerClient.java

Line 248: contains eats much time after serveral minutes

clearing requestedMobHats after some time/amount/(moved away) should fix it.

How expensive is it to request a mob hat again in that scenario.

Edit: http://docs.oracle.com/javase/7/docs/api/java/util/ArrayList.html#removeRange%28int,%20int%29 this could do it loosing only a part of array :)