Steps to clear the system cache.
1. Turn off the Galaxy S7.
2. Press and hold the following buttons at the same time— Volume Up, Power and Home. Wait for the Android logo to show up and for the phone to vibrate.
3. Let go of the Power button even as you continue to press the Volume Up and Home buttons.
4. Use the volume buttons to scroll down to Wipe Cache partition.
5. Press the Power button. Scroll down to Yes then press the Power button again.
6. Scroll down to Reboot System Now, then press Power button.
That’s it. The Samsung Galaxy S7 will reboot with a cleared system cache. Your phone should now work faster.