Konstantin Kovshenin

This plugin lists the top 100 slowest actions and filters during a page request in WordPress. It helps you figure out performance bottlenecks in themes and plugins.
Requires <a href="https://wordpress.org/plugins/debug-bar/" title="Debug Bar" rel="ugc">Debug Bar</a>.
Current limitations:
<ul>
<li>Does not time nested actions and filters due to a core bug</li>
<li>Does not time actions and filters before plugins_loaded or muplugins_loaded if placed in mu-plugins</li>
<li>Does not time actions and callbacks after wp_footer at priority 1000</li>
</ul>

Debug Bar Slow Actions

many thanks to author. Excellent plugin!



MUST-HAVE for every developer.

Great!

This plugin is essential for plugin development! It also works with the Query Monitor plugin.

Indispensable!

Easily find out which actions and filters are the slowest during a page load.

tombenner

MySQL Profiler displays debugging information about SQL queries to admin WordPress users. For each query, the profiler displays the time, syntax-highlighted SQL, and a trace of the functions (as well as the file and line number that the functions were called from) that were called.
The list can be sorted by any of its columns, so you can, for example:
<ul>
<li>Order the list by ID to see the chronological order of the queries</li>
<li>Order the list by time to see the slowest queries</li>
<li>Order the list by query to group the queries by type (SELECT, UPDATE, etc)</li>
<li>Order the list by trace to group the queries by similar origins</li>
</ul>
The list can also filtered by typing in the search box, so you can, for example:
<ul>
<li>View all queries that use the wp_posts table</li>
<li>View all queries that are related to the use of a function in taxonomy.php</li>
<li>View all queries that are related to the use of a specific function or class</li>
<li>View all queries that call a specific MySQL function</li>
</ul>
To turn off syntax highlighting, put the following in wp-config.php:
<pre><code>define('MP_HIGHLIGHT_SYNTAX', false);
</code></pre>
To omit the file and line number from the function trace and display the functions as a comma-separated list (to save vertical space), define the following in wp-config.php:
<pre><code>define('MP_DISPLAY_FILES', false);
</code></pre>
This plugin was loosely based on <a href="http://bueltge.de/" rel="nofollow ugc">Frank Bueltge</a>‘s <a href="https://wordpress.org/extend/plugins/debug-queries/" rel="ugc">Debug Queries</a> plugin, so a hearty thanks to him for the development of that.
If you’d like to grab development releases, see what new features are being added, or browse the source code please visit/follow the <a href="http://github.com/tombenner/mysql-profiler" rel="nofollow ugc">GitHub repo</a>.

MySQL Profiler

Displays a list of each page's SQL queries and the functions calling them that can be searched and sorted by time, type, etc.

Debug Bar Slow Actions vs MySQL Profiler