I played around with it for a bit and thought it was quite cool. Then just as I was about to click close I saw the wierd slider thing at the bottom and though - ah that would be so awesome if I could slide it and.... OH COOL!
I read this and slided to an earlier time. Now it's difficult to get back to the current time. Dragging the slider to a future time or clicking to the right brings me back to the earliest simulated time. Using Chrome 2 and it isn't slow.
Same issue here (using Chrome 2 as well :D). However for me the slider stayed at the earliest time but the updates appeared correctly in real time.