I'm having this issue as well, when I open up the game and go to the main menu everything is fine, but as soon as I start or load a game my processor use skyrockets, all the fans turn on, processor temperature shoots up to 80°C. The game itself works fine but no way in hell I'm going to play a game that makes my processor run that high. And I don't buy that it's the "quantity of assets loaded", because when I press ESC to open up the menu it goes down instantly, and the menu is just an overlay that doesn't unload the game's assets behind it.
My computer is pretty high-end (i7-12700KF + RTX 4080 SUPER) and should definitely not be sweating to run a game like this. After trying out a few things, by capping the game to 30FPS in the NVIDIA Control Panel I was able to make it run without melting my processor. So there is definitely some runaway calculation tied to the FPS running in the background while the game is unpaused that is way more intensive than it probably should be.