overheat

If you're running the sims with custom content and a large population then it's always fully utilizing multiple channels during operations. The only variations are the duration of operations and the amount of graphic and system memory which is consumed. If this is only causing overheat while the laptop is plugged in then it means your operating system has been configured to conserve power while on battery by throttling processing components. The solution is to clean your laptop and ensure that it can process your game content in a timely manner. Despite the appearance of excessive optimization, the sims is a very processor-intensive simulation and it demands the maximum of every component, including your drive controller during loading of packaged content, list processing, updating and insertion of neighborhood data, routing of actors, triggering of scheduled events, and general timing of world tasks and events - the sims is always 'clocking' and if you had monitored processor activity with each version you would have noticed this. This is a standard problem with all simulation and you can only solve it by managing process time and reducing the heat production rate of components (or increasing dissipation capacity which is very ugly, especially for AMD components).