Which apps should I greenify?

A: In short, don't hibernate all (or most of) your apps. App Analyzer of Greenify only shows apps which have POTENTIAL impact on battery consumption or device performance (click the icon "i" of each section for more details), it doesn't mean they actually have. You are suggested to only hibernate those you seldom use, plus the apps you are sure have negative impacts, most probably identified by the "Settings - Battery" of your device, or 3rd-party diagnose apps, such as Wakelock Detector and BetterBatteryStats (for power users).

The newest version of Greenify (3.4+) will identify some "background-free" apps in Greenify as "No need to hibernate" and not hibernate them by default. Background-free apps should hardly impact the battery consumption or device performance. Still you can force the hibernation by manually hibernate it once and tick "always ignore background-free".

Background Knowledge

"Running in background" does not mean it has definite impact on battery consumption or device performance. Experienced developers can also reduce the memory footprint of background service as low as several megabytes, which is negligible in most middle-to-high end devices with 1~2G RAM.

"May slow down the device" also does not mean it has definite impact on device smoothness. Android caches the process of apps regularly run, thus significantly reduced the cost of launching it in background.

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