Lo-Fi Games

As the title says, I've been experiencing some severe slowdown issues whenever the characters in my party separate from one another. I started with the scenario that gives you a small party and some building supplies (Freedom Seekers?) and built a small outpost with the intention of using it as a base for a small party of wandering badasses. I've found, however, that if I leave some members of the party in the outpost and send another party away, to sell some rum in a nearby town for instance, then the game slows down significantly. If the away party gets into a battle? Then the game begins to lag to the point where it is unplayable, with a framerate that drops below 1 fps.

I've been trying to keep the party all together as much as possible, but sometimes it just doesn't work out. The last time I played my outpost was attacked by dust bandits as my party was still recovering from wounds they had taken fighting another party of bandits just a few minutes prior. I hid behind my walls and hoped that they would wander off, but instead they smashed down the gates and stormed the place. It was all very exciting, but after all but one of my party members dropped I decided to make a last desperate attempt to save my little outpost. I sent the remaining squad member, Clifford, running as fast as his injured legs could take him toward the nearest city, taunting the bandits as he ran. All but one of the dust bandits chased him, but the closer he got to the city the slower the game became. By the time he reached the gates, bandits hot on his heels, it was impossible for me to tell what was going on, or influence what was happening.

My computer isn't so terrible that I'd expect slowdowns like this. I can run Skyrim at a comfortable framerate, and I'm running Kenshi on very low settings, graphically speaking. I'm not sure what is causing these slowdowns, since the game seems to unload models that I can't see. At least that's what I'm assuming happens since it takes a few moments for characters to "pop in" after I snap to them from a different cell.

Are there any settings that I can fiddle with to offset these slowdowns? Is this an issue that anyone else is having? Should I just play a game with a single character and leave the town-building stuff alone, as cool as it is?

Do you play in windowed mode or full screen? Because windowed mode requires more from your computer, so you might benefit from playing in full screen mode.

To me (at least last i chekced) seemed to be the oposite, i had a good ammount of FPS, then i tried fullscreen and got worse than how was

And Chris did a recent post advising not to do that due to the memory stuff or how was, not full sure now how he wrote.

It's a known issue that on almost every setup, windowed mode will approximately halve your frame rate. Here are some things that can improve your fps:
Run in full screen mode.
Turn shadows down or off. Shadows at the highest resolution and range will tax any setup, including my gtx 690.
Use vsync. It clears up a lot of graphical issues and keeps your fps at a more balanced rate.
Turn FXAA off. You really don't need it if you play in higher resolutions anyway.
View distance down. I run with about 7k terrain distance, and only 4k NPC and shadow distance.