John Murchison mentioned this in another post, but AI like that pictured isn't default. If you ran FS9 default AI at levels like that pictured you too would have poor fps

One day (

) someone will release a decent set of AI for FSX, and when they do with the lighter models that are available aftermarket for ai, you'll find you'll be able to turn up ai in fsx as well. But default, I for one fly around with almost empty airports until that day comes.

To quote John:
AI TRAFFIC - nothing new here, MS has been producing models unsuitable for AI since FS2002. If you remember back to when FS2004 was released it was generally accepted the aircraft were no good for mass AI. Thats why Project AI and people like me with AIS-AI became so popular with framerate friendly models. I developed AIS-AI because standard FS9 models killed my system. Try filling up Heathrow with 120 default FS9 models on a top-end computer system of the day, and see what happens. FSX is no different. Replace the FSX models with PAI or my AIS-AI models and your in business, just like FS9.Edit: I also reworded my post, I didn't want to imply "we" as a general collective of virtual pilots should move to FSX, I meant to say that I might move on from FS9.
Regards,