We've covered how to disable App Nap on an app-by-app basis should you find the OS X Mavericks feature interfering with some desired features or performance of a background app. If you are on a Mac desktop, however, and don't care about the battery life gains that App Nap delivers, then you can disable the feature across your entire Mac.
To do so, fire up Terminal and enter this command and hit Enter:
defaults write NSGlobalDomain NSAppSleepDisabled -bool YES
Any apps that are running need to be restarted for the change to take effect, or you can simply restart your system to disable App Nap for all of your applications.
You can use Activity Monitor to check to see if any of your apps hidden from view are using App Nap. Open Activity Monitor, click on the Energy tab and take a look at the App Nap column.
To reverse this change and bring back App Nap, use this Terminal command:
defaults write NSGlobalDomain NSAppSleepDisabled -bool NO