I am playing the snapshot on a free server, its a little laggy.
the problem is: when i enter on a nether portal (on a laggy server), it keeps me teleporting between the dimensions. i can't move, before i do, i am teleported again.
far as i remember, the portal cooldown on previous versions take more time.
this bug makes the player become stuck and don't let it play again until a adm removes it from the portal.

Server played: aternos.org
its a free server
EDIT: I just tested the 1.8.9 and the 16w02a version on offline mode. When you enter the portal and reach the nether, you will not return to normal world until you leave and enter the portal again.