CPU usage when monitor is turned off?

Question

Monitors

Sometimes, when the monitor is turned off when idle or if some task is being performed, but not difficult, I notice that the cooler starts to gain momentum. Tried several times to catch the process, but the download always falls very quickly as soon as the screen lights up. I once read that when idle, Windows starts compiling .NET libraries.
Actually, I want to understand whether this or the process that is running starts using more resources when the screen is turned off, or whether Windows really wastes processor time for its own needs.

Answer 1

Maybe you have some kind of encryptor Trojan running there, quietly? :-)