This plugin hasn’t been tested with the latest 3 major releases of WordPress. It may no longer be maintained or supported and may have compatibility issues when used with more recent versions of WordPress.

WP Rocket | Simple LoadCSS Preloader



This plugin is deprecated and will be removed in the future.
It was coded back in 2019 when WpRocket did not have asynchronous support for CSS.
Although this plugin operates at a lower level (main php buffer), which helps apply loadsCSS to ALL styles regardless of whether they conform to wp_enqueue or not, we recommend instead using WpRocket’s system: Load CSS Asynchronously.


Simple high performance plugin to enhance WP Rocket’s css output to use the loadCSS preload polyfill.
This will ensure any css being loaded via the page output is deferred, and utilizing a preload [rel] attribute.
Note: This will not affect admin pages. It’s designed only to process front-end pages.

It is recommended to enable the WP Rocket setting for “Optimize CSS”, which will provide your pages with inline Critical-CSS.
That way an unstyled flash is not seen on page load (if properly configured of course).

This plugin will boost your Lighthouse and PageSpeed Insight scores.

Plugin Mission

We hope that WP Rocket will implement this as a feature of their plugin.
The existing Load CSS Asynchronously only works for supported wp_enqueue styles, which not all plugins/themes properly utilize.
For normal users, we recommend using WP Rocket’s system instead of this plugin.


  • If you intend for logged-in users to see the effect, you must enable WP-Rocket’s setting called “caching for Logged-In Users”
  • Alternatively, you can run the plugin without WP-Rocket, despite it’s intended purpose. (>^.^)>


  • FilamentGroup’s LoadCSS(v2.0.1) inline injector
    (optional – see settings page next to WP Rocket), triggered via wp_head
  • High performance Regular Expression approach to process WP Rocket’s (php’s) output buffer, to replace stylesheets with the appropriate loadCSS syntax
  • Option to enable the buffer processor when you don’t have WP Rocket installed.
    ** This will respect AMP pages, and Yoast Sitemap output (by not executing). No other considerations have been implemented.

No fluff. Just a robust loadCSS implementation.

You can see how it works, & measure the performance, with this(via Run the Plugin’s code
Just paste your own page’s url or html into the appropriate variable @ the top.

And you can test this plugin’s regex as well: html – links filtered by regex

Github link is here: Click

Last tested with:

  • WP Rocket 3.13.x
  • WordPress 6.2.x


  • WP Rocket (optional via settings)
  • file_get_contents() php function (if included loadCSS lib is used via options — default = yes)


  • Settings Page
  • Resultant HTML
  • Sample Measurement
  • Sample Regex


  • Where are the settings?
    Right next to WP Rocket underneath the standard WordPress Admin -> Settings
  • Can I use this without WP Rocket?
    Yes, just make sure and check the box to do so under settings.
  • What ignore conditions are supported at this time?
    Yoast XML sitemap, and AMP pages. By default all Admin pages are ignored.


فبروري 26, 2021
Completely killed site. Could not connect to database after activation. Had to manually remove from plugins folder to resolve.
Read all 2 reviews

Contributors & Developers

“WP Rocket | Simple LoadCSS Preloader” is open source software. The following people have contributed to this plugin.


“WP Rocket | Simple LoadCSS Preloader” has been translated into 1 locale. Thank you to the translators for their contributions.

Translate “WP Rocket | Simple LoadCSS Preloader” into your language.

Interested in development?

Browse the code, check out the SVN repository, or subscribe to the development log by RSS.



  • Fix for rare but possible scenario where plugin could crash if function isn’t available. is_plugin_active()


  • Fixed bugs with get_option() variable usage(proofing conditions), wrapped executions in try/catch to prevent potential for an exception to bubble up and crash site, and added logging for exceptions.
  • Adjusted readme to indicate DEPRECATED status of this plugin, being that WpRocket now has an asynchronous css loader.


  • Adjusted the main runtime to utilize better detection for string replacement, to handle more scenarios (just in case).


  • Release date: October 29, 2018