How is this possible?

First of all, I have tried every possible combination of settings in the world and cant explaine this one. I use Ultimate Traffic for FSX and overall am pleased with it but have never found a good set of sliders that allowed me to show the traffic in all its glory and also have more that normal slider setting for scenery. Now I know I probably wont be able to do this at KLAX or such but I have found that if I crank up the scenery to max, normal AG, and 100% AI, yes I said 100% AI I get better performance not higher FPS but smoother performance than any other combination I have tried. Airports like Tampa Int, Palm Beach, Fort Lauderdale, Jacksonville, St Louis are what I have tried so far. I stopped there to post this and will try more later but couldnt understand why the performance stayed good. I am running mid level terrain, Normal AG, Max Scenery, 100 AI, no ground traffic cars or airport (they always get in the way). I am also using AI Smoothe which might be helping as well. Does anybody have an explanation, I swear Im not lying!