Tutorial for wiping the cache files. Check out how to delete temporary cache files. What's really important this operation won't delete your personal files.
www.hardreset.info
. . . As well as in each individual app you've been having lagging issues with?
If that doesn't help, then see if the lagging persists in Safe Mode: https://www.samsung.com/us/support/answer/ANS00062983/. If it goes away, then you know that something you installed is causing the system to bog down.