Crazy game lag with large unit stacks?

[daego]

I'm just in single on a large map with quite a few enemies. I started attacking one on two fronts (he's small, trapped against me and a peninsula) --two stacks of units with roughly 10 or 12 each. It was all fine until I took my first city from him. Now if that city comes onto my screen I drop to about 1 frame redraw every 3-4 seconds. This includes responses to UI clicks, hotkeys, etc. This basically destroyed that game. :-(

It may be related to the "smoking" graphic of the city.

Anyone else seen this?

[daego]

Note that I restarted the game twice. The lag was still there after restarting it. I went into Options and disabled "Effects". The city is no longer burning and the lag is no longer there.