digitalapps

This plugins detects all of the styles queued via wp_enqueue_style. Contents of each css file are copied and stored in a single css file. This file is loaded on the frontend. The plugin wp_dequeue_style and wp_deregister_style all other css files. The result is your website only makes one single http request to load css styling. Bonus feature the contents of the css file are minified.
Simply flip the switch and the plugin will do the rest.
NOTE: I have only tested this plugin on my own sites running the AdSense Theme. If you encounter a problem with this plugin please let me know. I will be able to help you.

WP CSS Merge

This plugins detects all of the styles queued via wp_enqueue_style. Contents of each css file are copied and stored in a single css file.

Arevico

Every admin wants to have their website loaded as fast as possible. A fast website results in more actions per visitors and higher conversions (signups, shares, reads, comments,etc).
<iframe loading="lazy" class="youtube-player" width="750" height="422" src="https://www.youtube.com/embed/gLMxXUETQOc?version=3&rel=1&showsearch=0&showinfo=1&iv_load_policy=1&fs=1&hl=en-US&autohide=2&wmode=transparent" allowfullscreen="true" style="border:0;" sandbox="allow-scripts allow-same-origin allow-popups allow-presentation allow-popups-to-escape-sandbox"></iframe>
CleanerPress tries to give you some more control over what is outputted to the user. It currently does te following:
<ul>
<li>Combine CSS stylesheets and caches it. Only static css files are returned to the user. – make sure to chmod the folder is needed</li>
<li>Remove the admin bar if you don’t want to have it</li>
<li>Hide version numbers, RSS, WLW endpoints to reduce html size and give hackers a harder time.</li>
<li>Loading all of your scripts via HeadJS. This means that the amount of request doesn’t matter, the website gets rendered 2-4 times faster. Will also be applied to the admin area</li>
<li>Load jQuery from the google cdn, so the visitor allready has it cached (well, 90% of the times)</li>
<li>select which plugins are loaded where 
** NOTE: All options can safely be enabled and don’t affect seo negative (speed is good). **</li>
</ul>

CleanerPress

Every admin wants to have their website loaded as fast as possible.CleanerPress tries to give you some more control over what is outputted to the user

WP CSS Merge vs CleanerPress