To get the same performance of SC3 you have to have the same use of the VC, 2mfd's and 1 hud.
Out of curiosity I tested a complete DG, with VC, in SC3 was 97 fps, in dll 56 fps , Mesh the DG is about 12,000 polygons, the most VC 11000 polygons.
Your ship has a much more polygons. Usually it is...