cgroups, to avoid jarring fan spin-up

[LinuxOnTheDesktop]

Is your feature request related to a problem? Please describe.
I'm always frustrated when on my powerful laptop and especially if I am watching video Timeshift makes the fans loud.

Describe the solution you'd like
CPU limiting automatically or by option. Cgroups can be used to implement this.

Describe alternatives you've considered
I do not fancy having to implement this myself: cgroups are complicated and making timeshift submit to them, from the outside as it were, would be no fun at all.