Lag/Latency Issues?

I'm running the newest update of Starbound on a mid-2013 Macbook Air. I've noticed that as I've gone further into the campaign, the game will lag to the point that it's unplayable. Monsters will teleport around the map, I'll freeze in place, etc. It doesn't seem like an fps issue, seeing that the fps itself is relatively stable, and mods I've gotten to fix this have improved the fps somewhat while not doing anything about my problem. I've also turned off vsync in the game files to no avail.

It appears to be when a lot of characters are onscreen at a time, such as in settlements. It's also especially bad when a character is following me around for a quest.

Is there anything I can do about this? I'm in love with this game and it sucks to see it fall apart like this. My machine has run much more graphically demanding games with no issues.

Mods I'm currently running (problems occur with and without):
No shadows (fps improvement)
FPS Booster

 

Mid-2013 Macbook Air
Running El Capitan (10.11.5)
1.3 GHz Intel i5
4GB RAM
Intel HD 5000 Graphics

Let me know if that's enough, I haven't done this kind of thing before.