Samsung Galaxy J8 is a very good mid-range phone. But many people have faced some lagging Issue in Galaxy J8 Device. Let's see how to solve this issue by performing minimal tweaks:
If you have downloaded any third-party launcher, consider to remove that. Because most of the launchers are not optimized for all mobiles. Launchers work good in some device and lags in some device. After removing the launcher, perform Hard Reboot i.e turn off your Galaxy J8 manually and start it again.
Uninstall All the Cleaner Applications from your device like Clean Master, Power Clean, etc. This application does nothing but increases your RAM consumption in background.
Uninstall some unnecessary Applications from your device you don't require or which you use less frequently.
Check your Application Running Setting in your Device and Force Stop the application you don't want. NOTE: Please don't force stop System Applications
If the problem still persists, you have to perform a factory reset. Go to Setting > Backup & Reset > Factory Reset
your phone. Make sure to take necessary backup.