With small or medium maps everything works ok, 60-75 fps.
With large maps, while "seeing" the same as in small maps, fps drops to 45 or less.
With clipboard open, fps drops by even 20.
Just a proposal, when you takeoff, drop (erase, delete, free) all the map except 6x6 surrounding sectors from your takeoff point, if you cross the limit, recreate again the 6x6 from the crossing point. While in tower, load the whole map. In GV, use only a 2x2 sectors.