FSX Weird FPS Drop issue

SO basically...I am there standing at gate D-42 of the default KLAS of FSX with the PMDG 738 NGX. Initial FPS stand at about 28-34. Now I start using GSX...

 

Deboarding done perfectly,

Catering, prefect,

 

But, by the time the Boarding Vehicles arrive, the FPS drops to 15-23.

The only other addon active is REX Esssential plus OD. Cloud texture res. at 1024x1024

 

FSX Settings:

 

Scenery: Dense

Autogen: Normal

Traffic: Air: 8%, Road and Water: 0, Airport Vehicles: Minimum.

Effects: All on High except for mesh resolution.

 

System Specs:

 

Win10 Home 64-Bit

NVIDIA GTX 660Ti

Intel i5 quad-core 2400 at 3.1 ghz

 

Please Help!:(

That's actually very good for that low-end rig. There's a lot of complex calculations going on in the background and co-incident processes running.

I know, that does work well for my system, especially because of that 3.1 Ghz processor. My Fps, After I noticed it today, seemed to drop to 5-12. Not 15-23. What I don't understand is, it works very well for the first ten minutes, but then the FPS drops like God knows what! Why should that happen even if there are complex calculations goin' on in the background? I mean, shouldn't the FPS stay very low from the very beginning in that case???

Many times it's AI traffic being generated in the entire sector that you are located.

Displaying 3d objects takes a lot of processing power.

AI aircraft around you, but also AI vehicles like cars drop the fps. The closer they are, the more it drops.