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.

ChrisHurst

MyWebsiteAdvisor

Simple Debug Plugin for WordPress analyzes the performance of your WordPress website and shows you the slowest performing functions. 
Also has the ability to display other useful information such as error log, PHP.ini variables, and DB performance varbailes. 
MySQL Database Optimization tool is also included. 
You can also enable and view the debug.log with no editing of wp-config.php file necessary!
Developer Website: http://MyWebsiteAdvisor.com/
Plugin Page: http://MyWebsiteAdvisor.com/tools/wordpress-plugins/simple-debug/
Video Tutorial: http://mywebsiteadvisor.com/learning/video-tutorials/simple-debug-tutorial/
We are looking for testimonials and live examples of our plugins on your website! 
Please submit your website or testimonial here: http://MyWebsiteAdvisor.com/testimonials/ 
If we choose your testimonial or website we can link to your site and generate some free traffic for you!
Requirements:
<ul>
<li>PHP 5.3</li>
</ul>
To-do:

Simple Debug

Analyzes WordPress website performance, helps to locate slow function hooks.

Debug Bar Slow Actions vs Simple Debug