CPU & energy
App Nap
macOS slows apps that are hidden and idle to save power.
What it is
When an app's windows are hidden and it isn't doing anything you'd notice (like playing audio), macOS can put it into App Nap so it uses less processor time and energy.
Activity Monitor's Energy tab has an App Nap column showing which apps are napping.
Should you worry?
No. It's a battery feature that works automatically.
What you can do
- Nothing to do.