Emperor slows down

[MrFlibble]

My Emperor slows down on later singleplayer missions. First I thought it was graphics and reduced the graphic quality to lowest possible, but it didn't help. I think that's because of a high number of units being on the map at the same time, cuz when I start the mission, everything goes okay, but some time after, when I build to advanced technologies (and the enemy does too) and have more units and structures, the game speed drastically slows down. I mean, both the game speed and the scroll speed. At the same time, the in-game menu animations (when the menu 'unfolds itself) go super-fast. Is there anything i can do? My computer isn't quite the slowest one, P4 (forgotten how many MGz, perhaps 1 GGZ? don't remember :O ), 256 Mb RAM, 64 Mb Video RAM.

[Nyarlathotep]

Make sure you've disabled shadows.