i accidentially found out that the official Redguard demo (wich was available for free when the game was released in 1998) was downloadable at the internet archive. i couldnt install it, since it wanted to overwrite my GOG version of redguard, but in the .rar archive if found the "RGFX.EXE" lurking around, and noticed that it was ~2 weeks "younger" than the original RGFX file, so i backuped the installed file, and replaced it with this one.
i noticed the following changes:

- the launch-loadingscreen showed the number 1.0.5.0 (instead of 1.0.1.0)
- the version-info panel (F1) now said "Build 5.0" (instead of "Build 1.0")
- in the distance, new objects appeared to load smoother, and now you couldnt see the sharp edge of the slowly rendering object anymore

Redguard always ran pretty smooth on my PC, but i saw many people complaining about performance issues, so i want to find out; can this apparrently improved file solve some problems? please download the demo here and report changes here https://archive.org/details/REDGUARDDemo

Edit: Wrong alarm, it turns out that the smoother rendering is caused by my custom value in System.ini at line "back_plane" with value 18000