JFK is our best selling scenery, and fps is extremely good considering the area is in, and is very well known for offering good fps, in an area that is already very slow, even without any scenery.
If we updated it to KDFW programming methods, the visual quality will surely improve, but the fps will not. KDFW is a very different airport, it's very large, but lives in a very fast area, and there's a lot of texture and objects repetition, which helps with fps a lot. JFK has 8 terminals all very different using very different textures, and this doesn't help with fps either.
You shouldn't use pre-set settings, but rather act on each setting individually.
Try to use this Website here:
http://www.venetubo.com/fsx.htmlIt will help you setting an optimal config for your system.