Hyperspeed

Whenever I enter a world, I get 1 or more seconds normal speed, and then everything happens at 2 times the speed or even faster. I cant fly in creative because i need to press space too quickly. This affects multiplayer, but only client side.
I dont know why this is happening, neither do I know how to get to this bug.
Please resolve this as fast as possible. This prevents me from playing minecraft.

EDIT:
after a random amount of time, my minecraft Freezes, so i get no crash log. This can be like 1 minute but it can also be half an hour