Consider using his plugin by default:
https://wordpress.org/plugins/index-wp-mysql-for-speed/
You only have to run it once, to create better indexing keys on the database tables, which in my eyes should be default in WordPress.
Unbelievable what I see in speed performance so far!
(Found this plugin actually by following the steps in this blog article for a client.)
But wait, there is more!
https://www.plumislandmedia.net/wordpress/performance/optimizing-wordpress-database-servers/