Ergonet Cache for WordPress is a free plugin developed by Ergonet srl, an Italian hosting company, to drastically improve the performance of a WordPress website by using a server-side page caching system (NGINX Cache or Varnish Cache).
BENEFITS
Using a server-side caching system increases your WordPress site’s performance by a minimum of 30% and up to 70%. Keep in mind that the actual improvement will also depend on your overall website optimization strategy.
WHAT IS PAGE CACHE AND HOW DOES IT WORK?
Page cache speeds up your website by storing the entire HTML of web pages directly on the web server, instantly serving them to visitors without needing to query the PHP server or the database again. Depending on your hosting plan, you can enable NGINX page cache (Equilibrio plan) or advanced RAM-based Varnish page cache (Progresso and Successo plans).
COMPATIBILITY
The Ergonet Cache plugin is compatible with all other website caching and optimization plugins, such as WP Rocket, W3 Total Cache, WO Optimize, etc.
The Ergonet Cache plugin functions solely as a communication layer between WordPress and the cache system (Varnish or NGINX) installed on the WordPress hosting platform (any plan) and dedicated cloud hosting (Solo and Multidomain plans) offered by Ergonet, available for purchase at this link: https://www.ergonet.it/hosting/hosting-wordpress-valore
A fundamental requirement for the plugin to work is enabling the caching system from the WebPanel (Ergonet client area available at https://webpanel.ergonet.it) by the user who purchased the shared or dedicated cloud hosting service.
HOW THE PLUGIN WORKS
Once the caching system is enabled from the Ergonet WebPanel and the Ergonet Cache plugin is installed and activated, it will work without any additional configuration.
Cache resource updates
Each time the webmaster updates a post or page, the plugin installed in WordPress will automatically delete the old cached version to prevent users from seeing outdated content.
At the same time, the homepage cache will also be cleared to reflect any new articles available on it.
Cache resource deletion
Thanks to the automatic update and removal functionality, there is no need to manually clear the cache. Moreover, forcibly clearing the entire cache is discouraged, as it would remove all previously stored resources (pages, articles, etc.) that had been frequently accessed.
On websites with a large amount of content, a full cache purge could also cause significant slowdowns due to WordPress needing to regenerate all requested pages or articles from scratch.
WHAT IS NOT CACHED
To ensure the plugin works efficiently, some resources and specific HTTP calls are never cached. These include:
- Any page, article/resource visited by a logged-in user.
- Any page, article/resource where a no-cache header or similar is set.
- All requests made to the WordPress backend.
- All data submission requests (e.g., registration forms, contact forms, comments, etc.)
HOW TO CHECK IF CACHING IS WORKING
The server-side cache system sets specific HTTP headers indicating whether the requested resource (link) is cached or not. To verify if your website is using the cache correctly, you must check for these HTTP headers.
It’s essential to ensure you are logged out of the WordPress site you’re checking, as well as from any other WordPress site open in other browser tabs. The first step is therefore to log out from the WordPress admin area.
Open the developer tools based on your browser:
For Firefox: Menu Browser Tools Browser Console
For Chrome: View Developer Options Developer Tools
Once the developer tools are open:
Select the “Network” tab
In Firefox, choose the “HTML” sub-tab, in Chrome, choose “Doc”
Refresh the website page
Click on the first row showing the domain name or visited link (with status 200)
In the right-hand column, you’ll see the response headers. The last header refers to the cache:
VARNISH CACHE HEADER
X-VC-Cache: HIT = the resource (page) is present in cache and was served from the Varnish cache system. This means the caching system is working properly.
X-VC-Cache: MISS = the resource (page) is NOT in cache and was generated by the WordPress application. This means the cache system was instructed by headers or custom rules not to serve the cached content to the visitor.
NGINX CACHE HEADER
x-cache-status: HIT or STALE = the resource (page) is present in cache and was served from the NGINX cache system. This means the caching system is working properly.
x-cache-status: MISS = the resource (page) is NOT in cache and was generated by the WordPress application. This means the cache system was instructed by headers or custom rules not to serve the cached content to the visitor.
ENABLING THE CACHING SYSTEM FROM THE WEBPANEL
The NGINX caching system is enabled by default and doesn’t require any specific settings.
To enable the Varnish caching system, we recommend checking the dedicated guide: https://docs.ergonet.it/gestione-hosting/impostazioni-cache-server/cache-varnish
