WordPress Speed Up can be achieved with a few database optimisations. Since your website is heavily dependent on your DB, meaning all its data is stored in your DB, should be the primary focus for your optimisation effect. Use this information as inspiration to improve your WP performance. Before you start, make sure you have a backup, just in case, ... you know ... "500 internal server error". 🙂
#1 - Reduce Database Calls
Reducing the database calls your site makes can help speed things up. Storing data in a database makes it easier to retrieve, and makes your website more flexible. This convenience can also sometimes cause your website to take up more server resources and cause your site to load slower. Unfortunately, there are a lot of poorly coded WordPress themes out there. They ignore WordPress standard practices and end up making direct database calls, or too many unnecessary requests to the database. This can really slow down your server by giving it too much work to do. Even well-coded themes can have code that makes database calls just to get a few basic information. Overcome these extra time and resource consuming calls with a child theme. Replace these database calls with your specific information to reduce all those unnecessary database calls.
#2 - Reduce Post Revisions
Post revisions take up space in your WordPress DB. Revisions can also affect some database queries run by plugins. If the plugin doesn’t specifically exclude post revisions, it might slow down your site by searching through them, unnecessarily. Yeah, happens. Keep you revisions under 5. Use Ctrl+Z (aka UNDO), when you notice immediate wrongdoing.
The upcoming recommendations should be done periodically (at least once a week), during a maintenance procedure. Automate as much as possible from these (scheduled to run daily), as it will reduce the time needed to clean-up the database weekly, and achieve a much needed WordPress Speed Up.
#3-6 - Posts cleanup
Revisions + Drafts + Auto Drafts + Trashed posts
#7-9 - Comments cleanup
Spam comments + Pending comments + Trashed comments
#10-13 - Transients cleanup
Dashboard Feed + Expired + Options + All transients
#14-18 - Remove Orphan data
Postmeta + Usermeta + Commentmeta + Relationships + Tables
#19-23 - Optimize tables (all, but these at least)
Logs + Options + Postmeta + Posts + Usermeta