Using the "WP Super Cache" WordPress plugin
WP Super Cache is a WordPress plugin that dramatically speeds up the performance of WordPress sites. Installing it is one of the steps we recommend for improving WordPress performance.
On this page:
- Activating WP Super Cache
- Configuring WP Super Cache
- Don’t use “Mobile device support” with responsive themes
- Don’t use “Enable dynamic caching” in most cases
- Don’t enable “preload mode”
- Don’t use “Clear all cache files when a post or page is published”
- Looking for even better performance?
- Enabling WP Super Cache for a domain name alias with mod_rewrite
- What about W3 Total Cache?
- What about WP Rocket?
Activating WP Super Cache
The plugin can be activated from within the WordPress “Dashboard” admin pages.
If you used our WordPress “one click installer”, the plugin is already part of your site and just needs activating:
- Click Plugins.
- Locate the line for the “WP Super Cache” plugin.
- Click Activate Plugin.
If you installed WordPress yourself (without using our installer), do this instead:
- Click Plugins.
- Click the Add New button.
- Search for the term WP Super Cache, then click Install Now when you find it. After installing it, you’ll be told that WordPress “Successfully installed the plugin”.
- Click Activate Plugin.
Configuring WP Super Cache
You should verify that the WP Super Cache settings are correct after activating it:
- Click Settings on the left side of the WordPress Dashboard.
- Click WP Super Cache under the Settings.
- Click the Advanced tab to set the caching options.
It will look like there are lots of options, but actually, configuring it is easy: click Enable Caching, then choose all the “recommended” options that you can check. Uncheck everything that’s not marked “recommended”.
In particular, do check these options unless you have a good reason not to:
- Simple (Recommended)
- Disable caching for logged in visitors (Recommended)
- Compress pages so they’re served more quickly to visitors (Recommended)
- Cache rebuild. Serve a supercache file to anonymous users while a new file is being generated (Recommended)
- 304 Not Modified browser caching. Indicate when a page has not been modified since it was last requested (Recommended)
- Extra homepage checks. (Very occasionally stops homepage caching) (Recommended)
And don’t check anything else unless you have a good reason to do so. It should look like this (we’ve highlighted the recommended settings for you):
When you’ve set things that way, scroll down and click Update Status to save the changes. You’re finished!
If you prefer, we’ll be glad to install and configure WP Super Cache for you, at no charge, on any copy of WordPress. Just contact us.
By the way, our instructions above recommend the Simple method because it’s simple to setup. The Expert method is a little faster (often shaving 10 milliseconds or so off the response time), but it’s a little more difficult to set up, making it not worth the trouble in most cases. It can be worth it if your site receives more than 10,000 page views a day, though.
Don’t use “Mobile device support” with responsive themes
Many people check the “Mobile device support” box thinking it’s required to make a site look correct for mobile devices, but that’s usually not the case.
What that box does is prevent sharing of cached HTML files between mobile and non-mobile browsers. That’s necessary if your site is set up to use completely different themes for mobile and non-mobile browsers, which used to be a common way of running WordPress. But modern “responsive” themes don‘t work that way: They don’t need this option because they send identical HTML code to all browsers, letting the browser decide how to display it.
So checking the “Mobile device support” box when you use a modern responsive theme is unnecessary, and it slows down the site for mobile visitors who don’t get to use a cached file from a previous desktop visitor (and vice-versa).
Don’t use “Enable dynamic caching” in most cases
“Enable dynamic caching” is only necessary if you use special extra plugins that hook into the “wpsc_cachedata filter” — without one of those special plugins, turning on this option does nothing except dramatically slow down the caching.
So unless you know you’re also using something else that relies on the “wpsc_cachedata filter” (which is very rare), leave this box unchecked.
Don’t enable “preload mode”
WP Super Cache offers a feature called “preload mode”. However, this feature disables automatic removal of old cached files, causing outdated pages to appear in some cases. This happens especially on the non-primary hostname of your site — for example, if WordPress thinks your site is at “www.example.com”, preload mode can cause outdated content to appear at “example.com” without the “www”.
For this reason, we don’t recommend using preload mode.
Don’t use “Clear all cache files when a post or page is published”
When you configure the WP Super Cache settings, don’t check the box marked “Clear all cache files when a post or page is published”. Using that checkbox effectively disables WP Super Cache for a few minutes every time you create a new post.
WP Super Cache should automatically clear changed cache files when a new post is published, without needing to also clear unchanged ones (which is what this box does).
Looking for even better performance?
If you didn’t use our “one click installer”, this tip will help (our installer already takes care of it): If your site doesn’t display different content when search engine robots index it, and you care about how quickly Google and other search engines think your pages load (you should), you can remove “bot, ia_archive, slurp, crawl, spider, Yandex” from the “Rejected User Agents” section of the Advanced settings — just make that space blank. This helps search engines get the same speed benefits.
We also recommend increasing the “Cache Timeout” to 172800 seconds in the “Expiry Time & Garbage Collection” section of the Advanced settings for the reasons described here, even though it suggests setting it lower for a busy site. Whenever you modify any page, that page (plus the home page and matching category and tag pages) are cleared from the cache immediately, so this will not cause your visitors to see old pages.
Finally, if your site has more than 10,000 page views per day, using the “Expert” method is recommended, because it can help performance when many visitors simultaneously load pages on your site.
Enabling WP Super Cache for a domain name alias with mod_rewrite
If you use the “Expert” method, and you enable WP Super Cache using a URL that’s a domain name alias, four of the lines that WP Super Cache adds to your .htaccess file may be incorrect. This is caused by a WP Super Cache bug.
Specifically, if your .htaccess file contains “/var/www/html/ex/example.com” in the RewriteCond and RewriteRule lines that were added, that extra text is wrong and should be removed. We can help you troubleshoot and fix this problem if you contact us.
What about W3 Total Cache?
“W3 Total Cache” is a plugin that tries to do the same thing as WP Super Cache. However, we’ve found that it’s harder to use and sometimes doesn’t give the same performance. Stick with WP Super Cache unless you have a good reason to switch. If you do use it, be sure to use our recommended W3 Total Cache settings.
What about WP Rocket?
“WP Rocket” is another caching plugin for WordPress. While it provides similar caching features to WP Super Cache, it also includes other features that increase the complexity of a WordPress site. As with W3 Total Cache, these extra features (which are usually unnecessary) make it more complicated to set up properly. We’ve had several reports of websites not displaying or caching properly due to complications with WP Rocket, and seen several cases where it actually increased the CPU usage of a site. Again, we recommend that you stick with WP Super Cache unless you have a good reason to switch.
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