I never knew that the setting for ground airport traffic in P3d could be set to zero with GSX installed:

 

http://www.fsdreamteam.com/forum/index.php/topic,13004.0/topicseen.html

 

It pays to read the manual. The GSX ground vehicles only provide services to the user's aircraft, so with the setting at zero, you won't see additional random cars and fuel trucks driving around aimlessly on taxiways. But if one likes that kind of thing ...

I like to fly with full realism but I turn on "ignore crashes" at airport so I dont get hit my ground vehicles while I'm programming the FMC etc. Once I'm lined up for takeoff I switch back to the full realism.