Before concluding there is something the matter with my system lets work it out together.
There's something "wrong" (not really wrong, but something that is causing this) with your system, it's certain, otherwise how do you explain my 51.2 fps, on the same video card and on a slower (not overclocked) system ?
You're assuming I am using all these products and mods. I do not use ENB series, only mogisoft shade.
I'm not assuming anything, you instead, assumed it was the airport that "eat your fps", but difference is, you know both your system and what you installed, I didn't, so I can only guess what you might start checking, like for ENB.
I never tried the Shade program, but it has a reputation for being lighter than ENB. However, that doesn't mean much, perhaps is not lighter HERE, on a scenery so GPU-dependent. Does it make any difference turning it off ?
What airplane you tested ? Does it make any difference with a default airplane ?
I am installing orbx blue, to see if it is anything with the fsx mesh that has corrupted for example.
The mesh shouldn't be an issue, and you would probably see terrain artifacts/spikes if the mesh had a problem.