Mike Jolley (a11n)

Testing your WordPress site? This plugin allows you to display memory, page load time and query count in the footer of your site on both the front-end and within admin.
This plugin is partly based upon the WP Query Counter by Steven Word (http://www.stevenword.com/plugins/wp-query-counter/) and has been customised for my testing needs.
If you’d like to contribute to the plugin you can find it on GitHub: <a href="https://github.com/mikejolley/WP-Page-Load-Stats" rel="nofollow ugc">https://github.com/mikejolley/WP-Page-Load-Stats</a>

WP Page Load Stats

Not sure why this only has 100+ users but this is a great tool!

Excellent!

Display memory, page load time, average load time and query count in the footer of your site.

Scott DeLuzio

AMP-MODE

Debug Info will provide you with information on your current WordPress operating environment. This is a helpful tool for you or a developer to use when trying to identify the root cause of an error, or other issue you may experience.
Debug Info provides the following information:
<ul>
<li>
WordPress version currently running on the site
</li>
<li>
Current/active WordPress theme name, theme version, theme author, and theme URI
</li>
<li>
List of active plugins
</li>
<li>
PHP version
</li>
<li>
MySQL version
</li>
<li>
Apache version
</li>
<li>
Full phpinfo() server environment information
</li>
</ul>
Thanks to <a href="http://firstsiteguide.com" rel="nofollow ugc">Ogi Djuraskovic</a> for the Spanish (es_ES) and Serbian (sr_RS) language translations.

Debug Info

A plugin to display your server's PHP info and WordPress environment data for debugging purposes.

WP Page Load Stats vs Debug Info