Forge12 Interactive GmbH

This plugin will track the load time of each plugin, javascript and css file 
to help you optimizing the performance of your WordPress site. It will help you 
to figure out which plugin / resource causing the slowness of your page.
Track time for:
<ol>
<li>Core</li>
<li>Theme </li>
<li>Plugins</li>
<li>Resources (JavaScript, CSS)</li>
<li>External files</li>
</ol>

F12-Profiler

Excellent! After P3 doesn’t work with PHP7+ anymore, F12 seems finally the one stepping in to fill that gap.

Update [18-Jun-19]. After some small contributions of mine to the dev efforts, the plugin developer has decided to add me to the team, long after this review was written.

Finally an alternative to P3

Trace the execution time of plugins, themes and core files to find the bottlenecks of your system.

Danny van Kooten

Basic profiler for WordPress Plugins. Benchmarks any given plugin by testing response times with and without the plugin activated.
<blockquote>
Plugin Profiler is on GitHub.
Bug reports (and pull requests) are welcomed on the <a href="https://github.com/dannyvankooten/wp-plugin-profiler" rel="nofollow ugc">Plugin Profiler GitHub repository</a>.
Please note that GitHub is not a support forum.
</blockquote>
<h4>Profiling a plugin</h4>
This plugin measures response times of any URL on your website in the following ways.
<ul>
<li>No plugins activated</li>
<li>Only the selected plugin(s) activated</li>
<li>All but the selected plugin(s) activated</li>
<li>All plugins activated</li>
</ul>
It then plots the response times in a chart and calculates the average response time time difference.
While this way of profiling a plugin is very low-tech it can be interesting to measure the impact of a plugin on your site’s response time. 
Please note that this way of benchmarking leaves a lot of factors out – like additional HTTP requests caused by a plugin, etc..
<h4>Installing Plugin Profiler</h4>
Since this plugin needs to filter out which plugins are activated for the profiling requests, it needs to be installed as a must-use plugin so it’s loaded early.
Have a look at the <a href="https://wordpress.org/plugins/plugin-profiler/installation/">installation instructions</a> for details.
More information
<ul>
<li>Developers; follow or contribute to the <a href="https://github.com/dannyvankooten/wp-plugin-profiler" rel="nofollow ugc">Plugin Profiler plugin on GitHub</a></li>
<li>Other <a href="https://dannyvankooten.com/wordpress-plugins/#utm_source=wp-plugin-repo&utm_medium=link&utm_campaign=more-info-link" rel="nofollow ugc">WordPress plugins</a> by <a href="https://dannyvankooten.com#utm_source=wp-plugin-repo&utm_medium=link&utm_campaign=more-info-link" rel="nofollow ugc">Danny van Kooten</a></li>
<li><a href="https://twitter.com/dannyvankooten" rel="nofollow ugc">@DannyvanKooten</a> on Twitter</li>
</ul>

Plugin Profiler

The plugin is currently working, and showing the load time of all plugins, no plugins, all but one plugin you specify, and that one plugin only. Pretty good for showing clients how much their plugins are slowing down their site. I like this plugin better than the p3 profiler.

WARNING: Copying and pasting the profiler.php file from the installation instructions will cause a white screen of death. You need to replace the quotes with normal quotes.

Works with WP 4.9

Basic plugin profiler. Benchmarks response times with and without a given plugin activated.

F12-Profiler vs Plugin Profiler