@ Danlisa - thanks - that fix got me back up to 60 fps and things look real good.
Now, one last thing (I hope). Can someone tell me where in the files the parameters are set for how the visibility/fog level affects the ranges at which ships can be spotted? I can't recall exactly what those ranges are (especially on the short end), but for example using the 16km mod it seems you can spot ships at about 16km in "no fog", about 8km in "light fog", maybe 2km in "medium fog" and maybe 400m in "heavy fog" type visibility. Using the 8 km version, it seems these numbers are about 8km for "no fog", 4 km for "light fog", etc.
Using the 8 km version, is there some easy way to change the "light fog" range to something more like 5 km instead of 4 km? Would doing that have any adverse/unforeseen impacts on anything else? Ideally, I'd like to set these ranges at something like 8km/5km/2km/500m for the various "fog" states - is that something tweakable using S3D? If so, where would those parameters be set?