Since the last firmware update you may receive the following message in the status bar of your Samsung Galaxy S6:
App optimization - Save battery power by optimizing the power consumption of apps that were not used more than 3 days.
This message comes from the following Android function: App Optimization
To manage the app optimization navigate into the settings menu:
Menu --> Settings --> Battery --> App Optimization --> Detail
Here are you see all apps listed that are automatically optimized by Android. A significant proportion of the battery consumption is reduced by this option, which means that you have to recharge the Samsung Galaxy S6 less often. Would you not like to use the automatic app optimization on the Samsung Galaxy S6, then you can disable it by using the controller.
You know now why this message appears suddenly on your Samsung Galaxy S6, what it means and how the app optimization in Android can be turned off.