Well to be more precise you will find it under advanced settings in the graphics menu, if you have'nt found it already.

As far as max SUPPORTED total troop count I'm guessing that would be 2400 men. Largest unit on normal troop size 60-62 men wich allows up to 1200 me per army. Using large or huge units would be a luxury and not supported unless it's found to be a problem on the programming side.

Now I can get 10,000 non-missile troops on a 1.49 GHZ processor in a battle with minor lag. Some other units will also cause too much lag for 10,000 men such as anything using phalanx. If I go for a mixed army I ca'nt go over 6000 troops.