The problem with the slowness is because Kongregate resizes the game. The original game dimension is 800x625 pixels, but because of the chat represented on the right side - the game was resized.
As a result of all above the Flash player needs to make additional calculations to interpolate the game graphics to the smaller size. My only suggestion in this case for all of you who experience slowness and bugs with the game to find and play it on another portals where it is represented in original size (Frozen Module or New Grounds for example).
I'm apologize for that. Frankly we tested it on different hardware including slowest PC and it was ok when it was without resizing.
Now when I tried to play the game here I see that my latest Core 2 processor works slow on soldiers movements. ;)
I'll try to update game later again with a quicker version.