Query Monitor for WordPress
Building a fast, flawless WordPress website is not always easy. If your website is suffering from performance issues, you will need to debug your code to find out what could be slowing down or breaking your site. Query Monitor for WordPress happens to be a powerful plugin that lets you debug plugins to find possible errors and slow queries.
The Query Monitor plugin shows all database queries performed on any given page. You will be able to see the time for all the queries and notifications for slow queries. The plugin lets you filter queries by type, component, and calling function. You can also see all the hooks used on the current page as well as the relevant files and classes.