Sometimes in a single player game -- usually on a large map, at least 3 (CPU) opponents, and during a "busy" time (many units visible / fighting) -- the game will start playing very rapidly, and there is no way to stop this. It becomes unplayable, unless I use the pause feature every few seconds.
Unfortunately, I can't trigger the bug reliably, although the three criteria above seem to do it. It appears related to the load being placed on the computer. This hasn't happened to me in a network game.
I haven't tested this on Mac OS X 10.8, so I don't know if the bug can be triggered there.