I would think if it's in another round, it's in another part of the map not visible from other rounds. If this is correct it should not be rendered anyway.
You can test what is rendered and what is not by loading your map, turning on sv_cheats ("sv_cheats 1" in console) and then turning on wireframe ("mat_wireframe 1" in console).
Anything you can see the wire frame of is being rendered at that time. If things are being rendered that you don't want take a look at some optimization tutorials.