Bug creating a new world on 1.8.1

on Minecraft for Mac it gets a HUGE BUG when creating a new world it builds the new world as usual the terrain etc but when you appear you are flying in a blue screen with clouds, then with the pass of a few minutes you appear on a world (it takes like 3 mins), it only happens when " Creating a New World on 1.8.1 ", but if you have an already created World you can play on it without any issues or even create a new world on 1.8 and then if you change the version to 1.8.1 you can still play on it, it only bugs when creating a new world on 1.8.1, then if you try to go to the title screen and save the game it gets frizzed its so annoying, actuallt it takes an eternity to unfreeze, i hope you can fix this as fast as possible Thank You it only happen in 1.8.1 to 1.8.2 pre 4