Upgrading to Marshmallow provides several "behind-the-scenes" improvements that enhance the performance of the device's Snapdragon 410 chipset and 2GB of RAM:

: Popularly ported to the A37f, it includes features like Dual Apps (running two accounts of the same app), Quick Ball for navigation shortcuts, and an improved gallery with cloud sync.

Calibrate battery – let the phone die completely, then charge to 100% while off. Also, disable Location History and turn off Wi-Fi scanning.

The Oppo A37f is a legendary budget device from 2016. With its 1.5GB of RAM and a Snapdragon 410 chipset, it was a solid performer in its prime. However, as app requirements have grown, the stock ColorOS 3.0 (based on Android 5.1 Lollipop) has become sluggish, laggy, and insecure.