iPhone 5s, iOS 8.0.2, show processes to check for battery drain

Hello.
I have an 5s, which battery drains quite fast.

I normally use Battery Doctor to find out which app uses too much power, but some apps give a "Not Returned" signal/name and the Activity Monitor like apps only list the running processes, but only sorted by PID and not CPU.

Is there a definite app for iOS or OS X to find out CPU usage by process name, as even the Settings app cannot help?

I attach a combined screenshot of the information I have. Settings says Solitaire uses a lot of battery, but Battery Doctor shows the name and to verify I just uninstalled it from my phone.
Closing all apps via the Switcher does not work, and even a restart after that brings back that Not Returned process.

And Safari does not scroll down when entering text below the visible text entry field on this forum.

Thanks for any pointers.

 

Just an update, though it will probably not bring me any closer to any answers, since this seems to be too specific of a problem.

That NOT RETURNED process did vanish for a while but did return after a couple of hours.
CPU usage is no at around 5 % but was often around 15 to 25 % when not doing anything except looking at the CPU activity.

I also went out at around 16:00 with the phone fully charged and came back at around 19:00 with 50 % battery life left.
I did use the phone to play a simple card game, Solitaire from FingerArts, while in transit for around 30 minutes at half display brightness.
I also did some browsing via 3G to look up various items and this issue and did post this thread and created four screenshots and used PS Express to crop the images and then another app to stitch them together, since PS Express cannot easily do that (at least I haven't seen the option) and MRF is not able to upload more than one image from an iOS device due to the file name (which confuses me, as different file names appear when downloading the photos and videos onto my computer).

Yeah, this is the gist of it.

If anyone can shed some light onto it, even a link, I will be thankful.

 

Who knows, but since it is not the only NOT RETURNED process, I cannot find out, since I haven't found another app yet to show CPU usage by process name.