What is it about TS4 that makes a computer run so hot?

Yeah, for some reason it feels like the game runs better in offline mode. Origin might be one reason.

My RTX 3080 seems to handle the game pretty well and the computer doesn't get very warm, not compared to some other games, I still get massive framedrops from time to time though and the game is very cpu intensive. I don't know how people manage to play this on old computers. At least not on older saves.