The Power Saving Mode is a very good feature offered by Samsung Galaxy S4 because it helps you to conserve your battery energy level for a long time. So, if you have to activate it, you will have to access Menu, Settings, More and Power Saving Mode. You will turn the slider button from Off to On and you will be able to adjust the following features:
CPU power saving is allowing you to limit the maximum performance of the CPU to conserve battery power.
Screen power saving is allowing you to use a low power level for your device’s screen to conserve battery power.
Turn off haptic feedback is allowing you to turn the haptic feedback option off to conserve battery power.
Learn about power saving is offering you tips about conserving battery power.