Are you sure that there's not something wrong on your end? I run every faction mod updated for 0.8.1 and I have never had any memory issues with only 4GB allocated.
You're running Dynasector, Nexelrin and all the compatible factions for both those mods using only 4gigs of RAM and you do not have any issues?!?! Can you post a screenshot of the mods you're using and a screenshot of your task manager while Starsector is running?! I am sorry, I dont want to sound rude but I dont believe you.
I am pretty sure my computer is not at fault here:
I5-4790k overclocked to 4.5, water cooled
GTX1080
16 gigs of RAM
Never had an issue with anything else before. I can post my dxdiag log if need be.
I did a few tests though and it appears that slowly the game just increases its memory usage as time passes. When I load my save from a fresh start, it starts at using about 6.5g of RAM and then slowly increases up to 7.8-9 gigs.
Thats not really normal at all. There IS really something wrong somewhere with the way the game uses RAM. To me it all indicates to some kind of memory leak.