Sorry, but 20 simple shapes in a scene should not have the same effect as running a game. What will happen when I inevitably expand the scene to have 100, 200 or 500 of those?
The reason I raised this issue is because I am encountering this problem using the Forge alone, but not, say, in Unity that has far more going on in an active scene. Playing a game like Armello also does not bring any temperature or resource-consumption issues either. So it cannot be a problem with the airflow.
But yes, it does not make sense that the CPU/GPU usage has been halved, but the heating up still proceeds. That can be explained with the screenshot timing though, so I should monitor it for longer period of time and see if that was the case. I will report back once I had the chance to do that.