This also depends of the stack size. Right, I understand what you're suggesting P, but what's it calculating after you've selected the stack? I'm talking about just clicking on a stack, not combat, not movement, not waiting for the computer to calculate the next turn -- just clicking on it. And as ...

2GB RAM + 2.4 GHz Core 2 Duo, so I don't think it's my hardware. And it's a *sustained* performance drop, meaning it continues for as long as the stack's selected, i.e. it doesn't get better after a few seconds.

Anyone else have the problem where you select a large stack and the game performance drops dramatically? Right-click (de-select) and it instantly returns to normal. Bug? Design issue? Something set in options that might remedy?