One consistent thing I've noticed with both Beta 1 and 2 is that after a while, perhaps and hour or more, the application tends to get 'weary'. Updates to code changes and general response time of everything begins to slow down. Eventually it comes to pretty painful crawl. Quitting and restarting the application does fix this but it is quite annoying. I'm on a MacBook Pro (2.26GHz) with 2 gigabytes of ram so the performance hinderance isn't from the hardware.