Same with me... after loading today's 'mini-update', I tried playing a quick match. It was fine until I alt-tabbed to go to chat. My frame rate went from 41 FPS to 17 FPS. I backed out of the game and rebooted to try to play another round, but ran out of time before I had to go to work. The game didn't totally freeze like it had been doing when alt-tabbing in online multiplayer, but this isn't much better. I'll give it another go tomorrow, and hopefully, I'll have more time to play then.