WP Speed of Light documentation


WP Speed of Light is a performance plugin for WordPress that gives a smaller loading time to all your pages.


Main advantages:

  • Multi-level folders
  • Move media with drag'n drop
  • Multiple media selection and move
  • Create galleries from folder
  • 4 gallery themes
  • NextGEN gallery importer
  • Import post categories as folder
  • Breadcrumb and folder tree navigation
  • Bulk upload in a particular folder
  • Nothing lost on uninstall
  • WooCommerce support



1.1 Install

WP Speed of Light is composed by a free plugin and another optional plugin PRO ADDON. In order to install our free plugin you should use standard WordPress installer or unzip the plugin and put all the folder in /wp-content/plugin.

Then hit install and activate



The install the plugin PRO ADDON and get the additional feature, login and go to your JoomUnited account here: https://www.joomunited.com/my-account
Download the ZIP archive of WP Speed of Light addon and install it WITH the free version (both need to be installed) using the menu:
Plugin > Add New > Upload plugin



Then click on activate plugin, to see WP Speed of Light menu appear on the WordPress left menu.

WP Speed of Light is accessible from the left menu but also though a top menu bar to clear the cache manually.


1.2 Update the plugin

In order to update the WP Speed of Light, you can use the WordPress default updater. You can also remove and install the new version from a .zip file downloaded on www.joomunited.com or wordpress.org. In any case you won’t lose any content because everything is database stored.



Be sure to always have the latest version to avoid security and stability problem.


1.3 Notification after install

After install you'll get a notification that enable cache and brings you to the dashboard automatically.




The dashboard of the plugin check all the performance of your WordPress website and how it's important to fix it. You can hover your mouse on each criteria to check the help tooltip. By now the Speed of Light dashboard returns the following information:

  • Check cache and compression activation
  • Check resources minification
  • Check resources group
  • Check the database cleanup
  • Return the latest website loading time test
  • Return the latest database queries check
  • Check for PHP version update
  • Other recommendations regarding the plugins (number of plugins...)



NOTE: Gzip compression is checked, it it's activated on your server the plugin will use it in priority, if not the plugin will activate it automatically using the server mod_deflate



3.1 WordPress speed test

To run speed tests we are using WebPageTest API. You can get free WebPagetest API key here: https://www.webpagetest.org/getkey.php
You can run up to 200 test per day on the same domain with a single API key, this is the only limit.

Check your email to get API key, and then copy/paste it in WP Speed of Light Configuration.


Select an URL to run the test then launch the test. It may takes few minutes because there's a queue system for analysis.



The speed tests check the following criteria:

  • First load: like a browser that had its cache and cookies cleared out, represents what a first-time visitor to the page will experience
  • Second load: test is done immediately after the First load test without clearing out anything



The others performance criteria are:

  • Loading time: page loading page time in seconds
  • First byte delay: Time from the start of the initial navigation until the first byte
  • Start render: Time from navigation start to first content
  • Caching: % of static assets served though cache system
  • Gzip activation: % of text or js assets that were gzip encoded/compressed
  • Image compression: % image compressed in the page


Based on that you can run several speed test on the same or different page and compare the results.



The more details button allows you to compare the speed test results in a single table (same URL comparison).



3.2 Database queries test

The database testing will determine if you have performance issues regarding database queries. Select a page of website and run the test.



You'll get separated results for WordPress core execution, plugins execution and theme execution.



3.1 Activate Speed Optimization

The Speed optimization section is the place to configure the tools that speed up WordPress. Use the menu WP Speed of Light > Speed optimization

  • Activate cache system: It will speedup your website by preloading common page elements and database queries
  • Clean each: Automatically cleanup the cache stored each x minutes and generate a new version instantly
  • Cleanup on save: Clean cache automatically when saving a WordPress content like post, page...
  • Cache for desktop/tablet/mobile: Serve the cache for desktop for all devices by default. The other option of specific cache per device has to be used only if your theme framework is generating specific files per device.
  • Add expire headers: It gives instruction to the browser whether it should request a specific file from the server or whether they should grab it from the browser’s cache
  • Remove query strings: Remove query strings from static resources like CSS & JS files inside the Header to improve your scores on services like Pingdom, GTmetrix, PageSpeed and YSlow
  • Never cache: Remove specific URLs from cache, it's useful when you have pages with AJAX data that require a cache always clean

You can exclude from the cache a set of URL using rules like: www.website.com/blog*


3.2 Resources Group and Minification

Minification refers to the process of removing unnecessary or redundant data without affecting how the resource is processed by the browser. E.g: code comments and formatting, removing unused code, using shorter variable and function names, and so on.

NOTE: Some options are only available in the plugin PRO ADDON. Use with caution and test your website, it may generates conflicts
  • HTML minification: Minify HTML cache files served by the plugin
  • CSS minification: Minify CSS files served by the plugin
  • JS minification: Minify JS files served by the plugin
  • Group CSS: Grouping several CSS files into a single file will minimize the HTTP requests number
  • Group JS: Grouping several JS files into a single file will minimize the HTTP requests number
  • PRO ADDON ONLY - Group font and Google Fonts: Group local fonts and Google fonts in a single file to be served faster




PRO ADDON ONLY - The file group and minification is one the tricky stuff to configure on complex WordPress website with tons of plugins and files called on every page.
First you need to to index your files called on your website, click on advanced file exclusion.



Then, select wp-content where most of your website files should comes from and Scan now.



A list of files classified by type (All, JS, CSS, Font) should be displayed below. If you've identified one files that cause trouble when activating the file group or minification you can exclude it from here by using a simple ON/OFF button.



3.3 Preloading and Prefetching

Those feature from the tab Advanced optimization are only included in the PRO ADDON plugin.

Cache Preloading: The cache preloading is the process of generating a first version of the page cache automatically, so the first user that comes to the page after a cache cleanup won't have to wait for the cache generation.
The page cache URLs specified, one per line, will be regenerated after a cache cleanup automatically.



DNS Prefetching: The DNS prefetching will pre-load DNS information on external domain links. For example, if your website is referring frequently to an external domain in hyperlinks, pre-fetching the DNS of this domain will load the page of this domain faster when a user click on it.



There are 6 tools to clean up the WordPress database.



  • Clean all post revisions: WordPress, by default, is generating content revisions (copy) to restore it from an old version. If you don’t need revisions, clean up!
  • Clean all auto drafted content: WordPress, by default, have an auto saving feature to restore content from the latest auto saved version. If you don’t need auto saved content, clean up!
  • Remove all trashed content: All content (post, page,...) in trash will be cleaned up.
  • Remove comments from trash & spam: All comments in trash or classified as spam will be cleaned up
  • Remove trackbacks and pingbacks: These are methods for alerting blogs that you have linked to them. If you don’t need revision, clean up!
  • Remove transient options: Transient is something like a basic cache system used by WordPress. No risk it’s regenerated by WordPress automatically.




  • Duplicated post meta: Remove duplicated post meta from the database
  • Duplicated comment meta: Remove duplicated comment meta from the database
  • Duplicated user meta: Remove duplicated user meta from the database
  • Duplicated term meta: Remove duplicated term meta from the database
  • Optimize database tables: You can use OPTIMIZE TABLE to reclaim the unused space and to defragment the data file.


The plugin PRO ADDON also add the possibility to perform automatic cleanup at a defined frequency (by minutes/days/hours).



First, you go to WP Speed of Light > CDN integration on the left menu.


Then you activate CDN, and fill your CDN information here.



  • CDN URL: Add your CDN URL, without the trailing slash (at the end).
  • CDN Content: Your WordPress content served through CDN resources, separated by comma. By default wp-content, wp-includes.
  • Exclude Content: Exclude file type or directories from CDN network.
  • Relative path: Enabled by default, Enable/Disable the CDN for relative paths resources. Used for some compatibilities with specific Wordpress plugins.

PRO ADDON ONLY - includes specific automatic cache cleanup for:

Siteground cache: cleanup the Siteground cache when a cache clean is performed
MaxCDN cache: cleanup the MaxCDN cache when a cache clean is performed

KeyCDN cache: cleanup the KeyCDN cache when a cache clean is performed

CloudFlare cache: cleanup the CloudFlare cache when a cache clean is performed

Varnish cache: cleanup the Varnish cache when a cache clean is performed






Display clean cache in top toolbar: Display a button in the topbar to clean all the site cache

Disable optimization for admin users: When an admin is Login you can disable speed optimization (cache, compression,...)

PRO ADDON ONLY - Disable optimization for: Also disable all speed optimization for specified user roles

Your WebPagetest API Key: Your WebPageTestAPI key goes here. It's required to run the speed analysis tool.