App Nap is a feature in OS X Mavericks which automatically pauses applications once they have gone unused for a period of time, helping to reduce energy consumption and saving battery life for portable Macs.

Though App Nap can make a big difference in extending the battery life of MacBooks, there are some unique situations where users may not want an application to pause itself when unused, inactive, or otherwise in the background. For these situations, you can selectively prevent App Nap by disabling it on a per-application basis. Most users should not disable App Nap without a compelling reason to do so.

Selectively Disable App Nap for Mac Applications

Quit the application you wish to disable App Nap for

From the OS X Finder, navigate to the /Applications/ directory, or whatever the parent directory is of the app you wish to disable App Nap for

Locate the application to disable App Nap for, select it, then go to the “File” menu and select “Get Info” (or select the app and hit Command+i)

Check the box for “Prevent App Nap”, found under the General section of Get Info

Close out of Get Info and relaunch the app in question

You must relaunch active applications for the toggled App Nap setting to take effect, whether you are disabling it or re-enabling it. This process must be repeated for each application that you wish to prevent App Nap for.

It’s safe to assume that all apps will use App Nap unless specifically directed not to using this trick.

Checking Which Apps Are Currently Using App Nap

If you aren’t sure what is currently utilizing the App Nap feature and what isn’t, you can see exactly which apps are suspended by turning to Activity Monitor, and going to the Energy tab:

For portable Mac users in particular, relying on App Nap really is one of the better yet simpler tips for OS X Mavericks, and should be left enabled for all applications unless there is a profound reason to turn it off.