This is correct. Unfortunately we struggle with optimisation still. We are almost forced to use Post Processing. Messing with the lights themselves (dynamic lights because static is.. static) causes to much performance issues. I've had contact with lots of other developers in UE3, most of them cheated by using a post processing scheme and a color lookup table. We also intend to use this, but, since there is the possibility of turning PP off, people might have a unfair advantage.
Therefore we decided to make a daytime version only of this map with static lighting. We also consider making a night version, but have static lighting. Especially since we have a lot of stuff in the map and the map itself is quite large.