There is something wrong in your configuration, my GTX560 is non Ti and I get 20+ fps at major airports with a ton of addons REX AS2012 NGX HD textures Trafficx at 40%. Autogen dense, scenery complexity maxed and texture res 7cm. Post your cfg file to check it. If you use DX10 you should get better fps, but is a complete mess that's why it's advised DX9.

I run FSX fine on a asus laptop with a nvidia GeForce GTX 560M.

Have tons of planes and addons The cfg file tweaks and nvidiaInspect

setup up have got to be done.

 

My laptop runs FSX better then my desktop with a overclocked i7 at 4.8

because of tweaking never bothered to do it on the desktop yet.