Belive me it's not problem in apps but in core system and sometimes awake state as far as I've investigated.
I have been looking for a magic tick box which will lower battery drain since 6.6.16, and failed.
Miui8 brings all the beauty and glory, but the basic use of smartphone is compromised while the major role of the battery is to generate heat...
In miui8 - I've disabled all of gapps services and feautures, disabled all of phone groovie feautures (double tap, rotation, auto brightness etc), disabled some draining applications (like Facebook), wifi always scanning off, disabled all emergency broadcasts, all system touch and dial sounds and vibrations, wake lock screen notifications, disabled gps, etc.
Q: Did that improve battery?
A: NO! (well, a little bit, nothing spectacular)
Q: Is that the way we want to use smartphone?
A: NO!
Q: Is miui8 worth sacrificing?
A: For me personally, no. I got enough of it. It's like being married to top model who is frigid and a horrible person
I've enabled all of thoose futures on miui7 and with all enabled battery time beats the hell out of miui8 with all disabled.
My next miui8 adventure plan is: backup, backup, backup > test stable rom battery and heating > possibly restore.
Also, I have two mi4c's, SWMBO is using miui8 developer and I will see and track if it improves. Luckily, for now her smartphone usage pattern is allowing 50% less battery juice on miui8 and I can make a direct comparison.
Besides miui8 bad experience, I am horrified how the possible Marshmallow update will be on mi4c, and people are (unfortunately) yealding for it.
Generally, in last few years in IT (one of my jobs) updates are not even close to what they are used to be...
Anyway, it does NOT dispute the efforts of developers from xiaomi.eu. Thank You developersm once more. They only take the core from china developer roms, and problem is present there also - in china developer rom. I am still on great xiaomi.eu ROM, but now 7.1.6.0 stable.