I not a dev or anything. But my understanding is that it all comes down to leveraging all the capabilities of 1 single hardware configuration. You can tune and optimize your code to extract every bit of performance out of the consoles hardware because the hardware (and software too I guess) doesn’t change. PC games are much MUCH harder to optimize. Users can have a near limitless variety of hardware, driver, and OS combinations that prevent such a high level of optimization.
It’s running pretty decent now since that lastest couple patches. But I haven’t pushed a city up past 60k population yet. I’m still a bit sore they didn’t implement bicycles. Should have been baked in at launch.