App Nap is a pre-installed feature in Mac OS X Mavericks that makes the apps not being used/inactive apps to go into a dormant mode, to save the battery power. And, while in the inactive state, these apps do not hinder the current processes.
Despite being a useful tool, some may find it to be a nuisance, as the paused apps require some time to return to the foreground process (to become active, basically). Enabling/disabling this app has an effect on all the apps or softwares available in your Mac.
How to Disable App Nap Completely in Mac OS X
Step 1: Make sure that all your applications are closed before you start the process, as disabling this option can affect your current process.
Step 2: Open Finder → Applications and then click on “Utilities.”
Step 3: Choose “Terminal” and type –
defaults write NSGlobalDomain NSAppSleepDisabled -bool YES
Step 4: Press “Return Key”
Step 5: Exit the Terminal and re-start your app or process you were working on.
To check whether the command string has worked or not, you can start the apps and not use them for some time. If they don’t go into a dormant mode, you know that the string has worked. Also, you can go to “Energy panel” within Activity Monitor. Over there, check the “App Nap” section, if the command has worked there will be a “No” displaying under it.
In case you want to activate the App Nap again, repeat the above process. And, in the terminal type
defaults delete NSGlobalDomain NSAppSleepDisabled and hit return. The App nap will start working again. However, this function can run in OS X 10.9 or later versions.