Thanks, I didn't think of checking neighbouring system names Ya, I saw in RandomObjects that CreateCarcass() isn't the one I was looking for. Do we need to comment out entire functions? I thought it's safer to comment out the line which does the actual LoadCloud() call.

I'll edit gefest location script and start a new game to check.

Edit:
Ok, weird. I thought the nested loop in function CreateRandomCloud() was responsible for spawning all that crap, right? But commenting them out didn't help. Turns out the culprits are the 3 LoadCloud() calls in section "--CLOUD", lines 63-65, which call LoadCloud() with "huge_cyl.cld". Huh. I thought that was a debris reference. Commenting these 3 lines out caused the laggy fog to not appear. Great. If all systems follow the same convention, then simply commenting out the LoadCloud() calls under the "--CLOUD" section will stop fog from showing up.

@lanelor:
The pitch black effect is used sort of like a scene fade out. Something like "come closer and let me tell you about it", then the scene fades to black. A few seconds later normal lighting is restored. Only seen it used in the InoCo endgame missions though.

Edit 2:
I've found a better solution than having to manually edit every single system script. Simply rename/delete the "huge_cyl.cld" file and the game won't draw anything since it can't find it. All done, no more laggy fog now. Does anyone know what format the .cld file is? Is it an image or something? It may be a better idea to replace it rather than just delete it.

Edit 3:
I cloned medium_station_ora.cld and renamed it huge_cyl.cld. Game didn't crash, but it didn't show anything strange as I was expecting either. There were smaller than normal patches of fog though. Replacing it with a copy of clouds1.cld simply showed nothing. So I guess you can either replace huge_cyl.cld with a copy of clouds1.cld or simply delete/rename it to get rid of the fog.

Caution, I haven't tested in other systems. I think there's also fog somewhere in Debris 1 and the Precursor map.