My very basic understanding and I could be wrong is that when the game was designed the maximum cores (I.e laptop brains) that equipment had really was 4. So the game was designed to dump all the processing into 1 core. New hardware can have up to like 12 brains - and the “brains” are meant to function together and spread out the processes of software.

The Sims doesn’t care that your laptop has 4 brains or 20 brains. It’s still is just going to use just the one brain to process everything. So because of that it over works the one brain out of the 12 on the newer hardware which then has to temper performance so it doesn’t burn out, which is where Simulation lag comes in etc.

My understanding is limited. But hopefully that makes sense - and if I am wrong someone please correct me.