It's likely an AFCAD issue.
Not an "issue" per se but, rather the usual convention of sceneries made so long ago, used by many other developers too, to flag parking spots as military combat to prevent default ground vehicles to appear in the scenery, and lower fps and interfere with the static objects on the gates. This worked because there's no military traffic in FSX and no commercial military AI packs, at least when the scenery was made.
We might flag those parking spots differently now.