*lol*
A Script?
If this was possible I'd sill use a 486 machine boosting it with a script.
Keeping FPS up is a matter of level design in first place.
Second place in your script (no addition stuff).
Using less time consuming functions, don't do everything every frame if not really necessary.
Removing level parts if not needed snice trace and move instruction need more time the more obejts are in the level (can be ~10 to 40 FPS with 600 entities less, depending on the script, too).
Use models with less polys, lowpoly does look very well, texture is much more important.
Use more models, level geometry consumes too much FPS.
Use smaller Terrain since the whole terrain has to be rendered even if only 20 polys are on the screen.
Keep lots stuff out of the view.
Just look at games like Half Life (1), Quake ect. they are complex, but there is not much on the screen.
Otherwise use iso view like I did in Dragonrise.
Models and Terrain, only the -simple- building is wmb: