First, our ground traffic uses multiple LODs, this means it both loads progressively less complex models in the distance and it also disappears entirely after a certain distance, this means it has a very low (if any) impact on fps. At the lowest LOD, the model is made with just a bunch of polygons, probably less than 20 or so. Just to give an idea, a *single* AI airplane might use several *thousands* of polygons...
That's why we don't need so much a specific option to turn it off that other scenery designers are forced to use, usually because they rely on the BGL format, which both lost LOD in FSX SP2 (due to an FSX SP2 bug that we don't suffer from), while we draw ground traffic in C++ using the Addon Manager, meaning we both don't suffer from the loss of LOD in SP2 (which affects BGL files only), and we have much flexibility in optimization depending on distance, which is not possible to control precisely in BGL, but we can instead.
On top of that, our ground vehicles responds to individual scenery complexity settings, meaning some of them will disappear when the Scenery Complexity slider is set below a certain level, and eventually they'll all disappear below that (I think at "Sparse" no ground vehicles will appear, and at "Normal" only 50% will ).
