Just wanted to share some info that some may not know, which I found out today doing some testing.....
At major airports, 'Aircraft tab: Aircraft casts shadows on the ground' checked will cause a large drop in frame rate ONLY with 'Traffic tab:Airport Vehicle Density' set On i.e. >None.
The reason for this are the in 4 'VEH_air_bagcart' folders/files within the SimObjects\GroundVehicles folder.
Normally for performance, you have to turn off the shadows or turn off the ground vehicles. You can have shadows with 'some' ground vehicles by moving out these 4 folders, then you can enjoy remaining ground vehicles (planes too of course!) with shadows On with minimal frame rate hit.
FYI, 'VEH_air_bagcart1' contains quite a few models, including the pushback vehicle.
All this info begs the question, what are the bagcart models doing that causes such a huge frame rate drop with shadows and can this be properly fixed?