AEon wrote:

I just read the link you posted, and I would imagine the bases, where all the action takes place have the lowest frame rate of the whole map.

You could also see it the other way around: have a target framerate you want hit throughout the map (on a certain piece of reference hardware), make sure the most detail heavy locations hit this mark and less important locations can be less detailed. The framerate in those places might increase, but that's not a bad thing, is it?