Small objects with 1 pixel in size far in distance are normally hidden by FSX, until the aircraft is approaching close enough. By expanding small objects with larger pixels to this hidden group could bring noticeable performance improvement.
SmallPartRejectRadius allows the specifying of pixel size of small objects to be included to the list.
This function does not appear in fsx.CFG by default. To use the function, add the following line under the [SCENERY] section.
The default value of “n” is 1 pixel. Recommended choices are 2, 3 and 4. A high value may cause unnaturally large amount of popping up of these small objects.
Some people report that this tweak doesn’t work after SP1. Try a larger value to see if it works in your system.
The value I am currently using is 2.