After highly increasing the random tick speed of the game, all the mobs seem to freeze in the same spot where the last time random tick speed was 1. Also, the spawn eggs used after increasing the tick speed have no effect and saving and quitting loading time takes forever to load after the increase in tick speed.
Duplicate of MC-84724.
Be careful when setting randomtickspeed too high. It will crash your game if your computer can't handle it.