The "Autogen" folder in FSX's main folder should have an Autogendescriptions.spb file along with two named "Autogendescriptions_Mid.spb" and "Autogendescriptions_Low.spb" (or something like that). (SP2/Acc only)
Renaming the currently active "Autogendescriptions.spb" to "Autogendescriptions_Max.spb" and renaming any of the other two (suggestion: the minimal one) to "Autogendescriptions.spb" should do it.
The Autogendescriptions.spb controls the variety in houses and trees. With a lower variety, the sim has to load and render less models which in turn should increase frame rates.
It allows me to run the maximum number of trees and houses per cell (6000/6000) without a (notable) frame rate hit.
