I already talked with Stef and LaLight about this: When I was playing multiplayer games yesterday, sometimes the game did kind of freeze during my opponents' turns. I was able to right-click on cards, but couldn't do anything else. I had to wait some time until the game showed me all the animations of my opponents' turns at once and I was able to do my turn as usual. A few times the only way to go on was to refresh the page and log in again. This did not occur when I played a single player test game.
Independently sometimes the chat did not update for five minutes or so. Then suddenly a whole bunch of messages appeared in the chat window.
There seem to be some connection issues, but my internet connection is fine. I use Firefox (newest version) on a Windows 8.1 notebook. I didn't recall the game numbers, but I always played on the frankfurt-test server.