Any ideas on reducing map file size?

[Patoman]

I've been creating a RPG kinda map with creeps wandering around. For some reason the map file size it 6000KB! The actual map size is 116x84 and classed as small. Could it be too many units\doodads? becuase i have got arount 167 and 3000 respectively. Or could it be the fact that all the creeps (most of the units on the map) are heroes? As far as triggers go, there are only 26 small ones.

Could you guys please give me a few ideas or hints on how to make it smaller? My aim would be about 4000KB so i can use it on a lan network. I have finished most other parts of the map but want to test it out in multiplayer.