If you've got a high degree of detail in the map then it's time to be concerned. Somebody made a highly detailed map in Unreal once and lost it because he couldn't open it because there was just too much detail.
See if you can't make some of the things in the map semi-solids or if they can be replaced with decorations.
See if you can't make some of the things in the map semi-solids or if they can be replaced with decorations.