First,
UNINSTALL DU BATTERY SAVER. It says "allows you to stop power consumptive background apps". That's another way of saying, "I have no idea how Android actually works, but I know how to write an app". (See
Multitasking the Android Way - I never argue how software works with the person who wrote it, since I can't read minds better than the person who owns the mind.) Killing "power consumptive background apps" that Android needs running (and there's no way an app can know what Android has calculated it's going to need) means that Android is immediately going to reload that app. Then DU will kill it again. Then Android will load it again. Then you'll wonder why instead of saving your battery, it's killing it. AND making your phone seem sluggish,
I wouldn't download any app that refers to killing (or stopping, the same thing) background apps. (It's one reason I don't write Android apps. I've been writing Java code since Java was released around 1995, but I don't know the Android environment well enough to be comfortable writing the app, rather than worrying about the environment - and that leads to apps that are, at best, junk. And I just haven's put aside the couple of months it's going to take to learn the environment that well. Retirement is exhausting.)
Once you uninstall it, your question will be moot. There are other, and much better, ways to save battery. There are dozens of threads here about turning off radios, finding out what's waking the phone, stopping background data transfer, etc.