I have an ASUS 72 laptop (nothing but graphic problems from the get go-BTW) I have noticed this game and others all of a sudden slowing down to blotchy graphics and slow performance. I usually have to reboot to get it back up to speed. UHG!I have recently noticed my civ5 crashing on the same turn and usually have to go back and redo a few turns to get a different result. this is new and not a problem at all a few months back.
However, I have noticed it mostly comes after taking a worker from a CS on either the next or second to next turn after doing it. This may be a clue to the programmers.
