Does it happens every time or on doing any particular task ? Regarding battery drain issue please refer to this thread and also do attach a ss of battery graph here ,
Main issue is draining my battery.. Even during idle it consumes battery. Can anybody please tell the procedure to roll back to miui 8.. Also whenever I press home button it is taking 3-4 seconds to load my homescreen. It really **s. By the way, mine is redmi note 4, 2gb 32gb version.
Thanks for sharing the issue with us,
Please do share your battery graph screenshot, so that we can know more about the cause for drain in your battery, and also please check which app is draining your battery and close that when not in use. ( Security app > Battery > Battery use > Apps ).
We also request you to run a full battery cycle ( Full charge and then discharge your charge to 1% and then charge your device to 100% ) .
Hope this helps you.Keep using MiUi and send us your feedback.
Thanks for providing us the screenshot please click on the clock icon on top right which is opposite to " battery use " and post the battery graph screenshot which will show the amount of your battery drain.
Please do understand that it is recommended to do a battery cycle after update for better Battery performance. (If incase of poor battery performance).
Thanks for writing the issues to us,
Please understand that RAM consumption depends on the applications that are Installed and running in background, please do check them and close them regularly when you don't need that app and also please stop unnecessary apps from auto starting in background. ( Security app > Permissions > Auto-Start ).
Regarding the documents app, it is designed like so in MiUi, however you can enable it whenever you need the app. ( Settings > installed apps > All > Documents and enable it ).
Your patience is appreciated in understanding the issue.