I wanted to share a little trick that seems to work for me. Don't know how useful it will be for others.
What I did was closing down my antivirus software, which is Kaspersky Internet Security, latest version. Obviously, I'm playing "offline" as it were. I'm using a "potato" laptop and the difference is like night and day. Before, adding any content mods was a struggle, and faction mods I simply couldn't handle having more than 1 (plus Nexerelin) without having constant drops in performance and VERY long loading times when starting (and closing, though not as long) the game. Now, the loading part still takes a while, but not anywhere near the ~20 minutes it took before and, while I'm still testing just how much I can get away with, content mods seem to have almost no impact on performance and several (2 or 3) factions don't seem to impact much either. Maybe I'll post somethin more specific, but for now I just wanted to share my experience.
Needles to say, shutting down your AV software is not recommended in general and one should do that at their own risk.
If this post somehow goes against any of the forum's rules, please let me know.
Edit: By the way, I wanted to ask a doubt I had but forgot to. It's about this section of this post's guide.
Loading is extremely slow!
This is usually caused by your graphics driver forcing vsync on for Starsector, which will cause the loading screen to take an extremely long time (a half an hour or more). Make sure that Starsector.exe and java.exe are set to not force vsync.
How do I do that exactly?