This is the Base file of Orbiter City to give you a better frame rate.
Have taken out the traffic lights,  windfarm, trees, benches and the bikes and cars.
The frame rate will be better but still Graphic Heavy.
If you still have a low frame rate take out all the mesh files but
leave the mesh with the file name "flat.msh" for
the underground parking in one of the buildings.
Hope this will help
Enjoy!!!