This plugin shows impact of installed plugins on your blogs' speed.

d3wp

This used, shows impact of installed plugins (only for those located in the official WordPress plugin repository) on your blogs’ 
speed. 
 In other words, with this plugin, you can easily determine which plugins from the WordPress 
plugin repository are less resource intensive, and which ones can slow down your WordPress blog when used.
The plugin shows four results (see screenshot):
<ul>
<li>Impact of the installed plugin on Google PageSpeed score for blogs’ Home page</li>
<li>Impact of the installed plugin on Google PageSpeed score for blogs’ sample Post page</li>
<li>Resources added to post page after plugin has been installed (in kB)</li>
<li>Number of DB tables created by the plugin.</li>
</ul>
More than 25.000 plugins were tested lately.
Every plugin was tested on a fresh WordPress installed instance populated with a sample content. 
No additional plugins were installed to avoid any unwanted impact on the speed test.
NOTE: 
This plugin calls <a href="http://www.wpspeedster.com" rel="nofollow ugc">wpspeedster.com</a> API to obtain necessary information about Speed Impact details. 
Only plugin slugs are send to the API, no additional or personal information is send.

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