December Update 1 - J7 16 buggy series

Dont know why samsung is doing all these. On 1st December, J7 16 received a 201mb update. After that when ever I press the lock button, it takes a second delay and then locks the screen. BUT WHY? Their is not a single option available for it.
What are the bugs after the update ?
Game qualities has been decreased, i.e the shadders.
Locking screen with a second of delay
WiFi Calling is currently if no use in India.
Battery gets drained much after October security patch

How to fix all these..??
1) You can flash the any official rom of J7 2016 released before August 2016.
2) You can wait for Samsung to fix all these.
3) Go for a new device.