How to enable WP_CACHE

Updated on October 22nd, 2020

Warning

Flywheel discourages the use of caching plugins, as they can actually decrease performance of the server level cache. For more information, check out this help article: What plugins are not recommended?

If you’d like to use a caching plugin on top of Flywheel like WP-Rocket, that plugin will need to create something called a persistent cache. The plugin will effectively dictate that the cache should never get rebuilt unless this plugin explicitly tells it to. In order to hand over control to the persistent caching plugin, you’ll need to enable a feature called WP_CACHE.

To enable this in the Flywheel app, navigate to the Advanced tab for your site and toggle WP_CACHE so the graphic is green and reads “On”.

Note

If you’re using WP Rocket, make sure “Activate Preloading” is turned off (unchecked) in WP Rocket settings, as this can lead to performance issues.

A note on Flywheel’s default caching setup

On Flywheel, our caching system helps make your site run blazingly fast while still allowing you to make ongoing updates to your site’s content and appearance that show up in real time. To strike this balance, the kind of caching we employ is non-persistent.

In a non-persistent cache, once all the pieces of a requested page are assembled after being visited and then are converted into a static snapshot. Each cached snapshot resides in our server’s memory for a set duration of time. This means that that short-term visits can simply pull up this ready-made page instead of needing to re-assemble every component of the page from scratch each time.

In this setup, after some time has passed, our system will clear this cache and then rebuild itself when a new visitor loads the page. Thus, we wind up with regularly updated content that loads quickly when you have more than one visitor to a particular page in a short window of time.