ACF (Advanced Custom Fields) is a plugin to create user-friendly custom fields. Visit their website to learn more.
Instead of saving the Field Groups setting into the database, you can do so in your theme folder.
I heavily recommend doing this because it improves the loading speed in both front-end and back-end.
1. Create /acf-json Folder in Your Theme

/acf-json
folder in your theme2. Done
Seriously?
Yes! now every time you save a Field Group, it will create a JSON file in that folder automatically.
For existing Field Groups, open all one by one and re-save them.

Conclusion
As stated above, you should apply this tip on all your sites that use ACF.
Not only for a performance boost, but it also helps with syncing different installations and version control it with Git.
Note: Sorry for the lack of update, it’s been a busy end of the year 🙂