What you do is open useroptions.ini and find the render distance line, it's probably set to -1.00000 (which means unlimited/server controlled or something like that). I turned mine to 300, which is super low (but my computer is terrible) you could probably try 1000 for a start, and go up or down from there depending on how well it runs. More then 3000 is probably a waste, and even as low as 300 is very playable (just don't try to fly because there's too much fog to see other planes or ground targets).
Thanks! This made the game almost playable for me at 800. I'll try piddling around with it more and see if I can make it good enough to actually be useful in a firefight. (It was good enough to medic a bit.)
Know any other tweaks like that that aren't ingame?
Glad it helped!
in the same file, you can change it to ShadowQuality=0, that will completely disable shadows which helped a bit for me. FloraQuality=0 and RenderFlora=Off should remove at least some of the plant life etc and maybe give you a few extra FPS.
Someone told me if you disable some or all of the sounds (set the slider to 0) it won't load the sound files at all and will give you a bit of a boost, but I didn't notice any difference at all doing that (if it helped, it was so minor it was not worth it). It can't hurt to try, though, maybe it will help you out.
You can also set render quality to lower then 50%. find the line that says RenderQuality=1 (or 0.5 or whatever) and change that to even lower, like RenderQuality=0.350000. Warning, this will make the game look *REALLY* terrible (
http://i307.photobucket.com/albums/nn284/GamestaRJ/40fps.jpg), but it might help you if your GPU is very old.
Another thing you can try is playing on easimir or amerish - the population is usually laughable unbalanced (like one side has 80%) but if it's relatively even, I find the performance is usually a LOT better there for me.
Also if you press control-f (or maybe it's alt-f I don't remember offhand) it gives you an FPS counter at the bottom, which will also list [CPU] or [GPU] to tell you which is bottlenecking your performance. Maybe not hugely helpful but if you plan on upgrading, it will let you know which to upgrade.