[2019] What are the biggest bottlenecks in Rimworld performance?

Hey guys, I am sure a lot of us here play with more mods than we can count (11+), and I am sure we have all reached a point in our base where the lag becomes too extreme and we are forced to start again. Well my computer is garbage for Rimworld apparently and that time happens way sooner than I'd like. I'm generally forced to restart before I hit "end game" because even going at 1x speed is laggy. It might be mods, or load order or w/e, but I've definitely seen people running way more mods with way bigger bases, and I try to avoid the mods that seem like they'd kill performance.

Thats why I'd like to know what hardware Rimworld relies on most. I am running on a gtx 970, 8gb of RAM and an i5-4590 for reference. Thanks to anyone.

EDIT: Also every like 2 seconds or so, my game freezes for like 0.25 seconds, as if its doing some big calculation. This is present in every game, and as I get a larger and larger base it gets worse and worse. Any ideas how to fix it?