Try clearing app cache (settings, storage, cache), and then shutdown and clear Davlik cache by holding home, volume up and power button until the Samsung appears, then release all but power button (I think that's how you do it --- otherwise search how to reboot galaxy S5 into safe mode)...and use volume keys to scroll down to "clear cache partition" and use power button to confirm...then reboot your phone normally. Some things may seem slow to launch for a day or two (gallery especially) and the battery can drain quickly while the device is recaching. Once you've given it 72 hours it should have recompiled most of the cache data...and you can see if the battery is any better. Fortunately they're only $10 shipped on Amazon if that doesn't help.
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