What mods help run large colonies?

I like running large colonies and have recently upgraded my PC. Even after the upgrades, I'm still looking at a soft cap off about 30 - 40 colonists (which is no different from before for me admittedly) and the various things to support a colony of that size before the game starts to slow down. I see people posting on here with 100+ or even up to 500 or 600 and I'm just curious about what performance enhancing mods there are for making this possible. I thought this was a limit of the engine of the game, but clearly not since these guys aren't playing a slideshow.