"DoMobSpawning" is causing reduced tick speed, causing general tick lag

The mobs are really slow, The slimes jump really slowly and if you hit a mob, They will jump away REALLY slowly. This is only affected for me in this snapshot. (snapshot 14w25b) Also redstone seems to be affected too :/. I am pretty sure it affects everything except players. [Or nothing but players] Also in snapshot 14w26b the skulls you place down are now white unless it is your skull.