Creepers / And mobs overall bad api etc

When creepers are charging up the explosions, the mobs don't run away when there supposed to.

All mobs have a bad api what I mean by that is, when you see a zombie and you get near it, they don't "notice you" or chase you, they just stand there not going after the player. (Its with all mobs including creepers).

Last issue: Performance (Can't really explain much, just needs more optimizations please!)