it started to happen when one of my minecraft friends joined me in my world. once i left said world and closed the game it was all fine. until i rebooted the game and went on the featured servers menu. i joined into the server and it was fine for about 10 seconds and then everyone in the lobby froze in place and i was the only one who could move around. this carried on for 20 seconds and then everyone unfroze  and moved about. 

i've also had this problem before on a greater scale were i couldn't join a server, world or friends world without it crashing.

thank you for reading this and please fix this soon.