It's happening to me nearly every time.The game freezes sometimes for seconds like:I click on one of my weapons in a fight,and the action happens some seconds later,or over the time limit.
But most time it fully freezes down,and i can't do anything,just refreshing the page.And then i move into my replays,and checking out the fight:It seems like the fight continued,and my rounds just passed,while my opponent have killed me.But it's also happening to my opponent too.He didn't do anything in his round,he's round just passed,and then was my turn.So i think other players are experiencing this problem too.
I think the problem is might be with the server.

If it's happened to you every time, then it's probably a problem on your end.

Possible causes could be:
-Bad internet connection (nothing you can do about this).
-Bad wireless signal, if you're connected wirelessly (move nearer the router)
-Slow computer (turn all the in-game options to their lowest values)
-Old game version (it should say ver 3.0B in the bottom right of the loading screen. If not, clear you cookies and cache).

If none of the last 3 help, where are you connecting from?
Also check you internet speed against a server in Dallas, Texas, USA [someone said that's where the server is, and no one has corrected them so far].

Try lowering your in-game graphical settings, sounds like your PC is freezing up.