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.

devmarvs

Block Weight Inspector adds a sidebar panel in the block editor that maps blocks in the current post/page to the CSS and JS assets they register. It estimates local asset sizes, highlights top offenders, and exports a JSON report. It can also generate a suggested conditional-loading snippet to help you dequeue assets when a block is not present. 
It also adds a Tools -> Block Weight Inspector screen for auditing existing posts without opening the editor. 
Note: The inspector preserves block comment delimiters when analyzing content so <code>parse_blocks()</code> remains accurate after sanitization.
Key features:
<ul>
<li>Block -> asset mapping using registered block metadata.</li>
<li>Estimated size for local assets.</li>
<li>Top offenders summary and full asset list.</li>
<li>JSON export for sharing or auditing.</li>
<li>Suggested conditional-loading rules (review before use).</li>
</ul>

Block Weight Inspector

See which blocks load which CSS/JS assets on a page and estimate their weight.

Debug Bar Slow Actions vs Block Weight Inspector