Comand and Conquer Generals ZH problems

hi guys im having a problem with CNC gen's ZH, wen playing a solo comp stomp on my own (not on the net) i get game lag on twilight Flame.
I just choose to do a 1v1 against 1 comp and get lag. At first I thought it might be bcos i was building to much as USA Airforce General, so i decided to be GLA Toxin and still the same, after about 10-15 mins the game starts to stop and start with lag, i dont know what is happening, the rest of the maps seem to be ok it is just twilight flame, i have rebooted, reformated, re-installed be it always happens. Can some1 help me get a full game on twilight flame without any lag.

Lag is a pretty broad term in this game: lag when you select a unit and its orders; the 'One or more players have disconnected' lag box; overall frames per second lowered?
Assuming it's the last one, try turning down all graphics settings. I used to find that the game actually progressed slower in singleplayer than multiplayer if my graphics were set too high, so this may be why it's more noticable you when play against the AI, plus TF is a big map, with a fair bit of detail so it may require a bit of extra ram compared to the other maps when on high settings.