> those with delayed whatsapp, do whitelist it in battery settings.
> those with so many bloatware apps and ads on their phone, wipe and flash official rom, you might using vendor rom.
> those trying on CM13, custom rom but fingerprint doesn't work, try check your fingerprint vendor, FocalTech is compatible, Goodix variant might not work
> before rooting or flashing other custom rom, do check did you unlocked your bootloader or not.

where did you bought ur redmi note3? if thorus set.just update your miui rom

should be mi malaysia set if you dont order from "imported" tag..just download and update
go to about phone-> tap multiple times until you enter CIT. Tap on Software Version..and scroll down. It should mention you're on FocalTech or Goodix.