If you are running a process in an app in the background while using other apps in the foreground, and the background app seems to be slow, then read on my friend. There may be a reason for that. Let’s see what gives.
Here is a definition of what App Nap actually does:
App Nap puts applications that you’re not using into a special low-power state that
regulates their CPU usage as well as network and disk I/O. App Nap can be automati-
cally triggered if an app’s windows are not visible and the app is not playing audio. . .
I did some research on Apple’s website and found this definition for macOS El Capitan, I am assuming it is the same for macOS Sierra:
App Nap helps you save power when you’re working with multiple apps at the same time. OS X can tell when an app is completely hidden behind other windows, and if that app isn’t currently doing something for you, such as playing music, downloading a file, or checking email. If the app is hidden or not doing something, OS X slows the app down. As soon as you start using the app again, it instantly shifts back to full speed.
App Nap was introduced in OS X Mavericks 10.9. The idea is it throttles down apps that are open, but are not being used. It was primarily designed for people using Mac laptops, but it can save energy of a Desktop machine as well.
The reason I am writing this article is I have been reading online where people are having trouble with apps that are running in the background while using another app in the front window. The app in the front most window is the app that is in “Focus.” During some of these discussions, people mentioned App Nap as the possible culprit. Well, maybe I guess.
In the old days, starting with Mavericks, you could do a Finder Get Info window on an app and check a box that said something like “Prevent App Nap.” Starting with El Capitan that capability has been removed by Apple. There are some utility apps that still have the “Disable App Nap” button in their Interface. Here is “Disable App Nap” in Onyx:
The utility app Cocktail has this setting as well.
During my research, I noted that you could look in the Activity Monitor app (Applications/Utilities/Activity Monitor) and see the status of App Nap for your applications. I did that on my wife’s El Capitan install on her MacBook Air and on my macOS Sierra install on my iMac. Here is what I found:
This is BEFORE turning off App Nap using Onyx! If App Nap is running, supposedly, the No’s would be Yes’s. So, what gives. Here is the bottom line as far as I can tell. We know El Capitan, and Sierra are using App Nap based on the above quote from Apple’s website. However, you and I cannot control it any longer. It seems that it runs automatically. Don’t panic, check out the underlined portion of the Apple website text. The key to me is the app in the background has to be idle! If I am running my QRecall backup in the background while writing a blog article, then QRecall is definitely not idle.
I have a request for you all. If you have some information on how App Nap works in El Capitan or Sierra please comment on this article. I am certainly not above making corrections or suggestions from your input.
If you think apps are slowing down while running in the background they may be, but that may be the way the app is coded. Or, it could be some other issue. According to Apple’s own description, if the app is actually doing something then App Nap is not the culprit.