I always had the fear, that fps would drop drastically when you look from your base towards the scrinship (or kodiak) with interior and at the same time the enemy base behind has to be rendered, too.
TS_OmegaCity for example is designed in the way, that the distance between the bases is high enough, so if you are in your base, the enemy base wont be rendered to save fps for the detailed city.
These are things you have to keep in mind, when creating a map. Otherwise the whole effort could be for nothing.