I had my tab names disappear on me too.
Once I started trying to play, selecting on the character creation screen was so laggy it was unplayable. (See video below)
Alt tab DID work for me though. At around 1 minute in this highlight, I alt tab and come back no problem. http://www.twitch.tv/itsnotmyfault1/c/4936117
The level up screen was similarly laggy. Didn't try playing the game much, but after loading one of the NPC's was stuck halfway in the ground.