How Joomla Caching Works
Caching reuses previously generated results
Caching improves performance by storing output or calculated results so Joomla does not have to rebuild the same information for every eligible request. Joomla provides administrator-controlled page, progressive, and conservative caching, and developers can also use Joomla cache controllers for application-specific data or calculations.
Joomla has several caching layers
Joomla Programmer Documentation describes three administrator-facing mechanisms: System - Page Cache, Progressive Caching, and Conservative Caching. Page Cache stores whole eligible pages. Progressive and Conservative caching operate at component-view and module levels according to Joomla's caching rules and the extension's implementation.
Conservative caching gives modules individual control
With Conservative Caching enabled in Global Configuration, cacheable component views can be cached and individual modules can use their own Advanced → Caching setting. A module that supports caching can use the global setting or opt out with No caching, allowing more selective control.
Progressive caching is more aggressive with modules
Progressive Caching also caches eligible component views, but Joomla's current programmer documentation describes module output as being cached together rather than controlled individually in the same way as Conservative Caching. This can improve reuse but is less selective.
Logged-in users are protected from these shared caches
Current Joomla Programmer Documentation states that Joomla performs no caching for logged-on users for these three mechanisms. This avoids serving cached output generated for one authenticated user's access context to another authenticated user.
Cache lifetime controls reuse
Global Configuration → System includes Cache Time in minutes. Cached entries can be reused until they expire according to the applicable cache mechanism. Individual cacheable modules can also expose their own cache-time setting, which Joomla documentation notes is expressed in seconds rather than the global setting's minutes.
Caching requires verification on the actual site
Enable caching gradually and test guest pages, modules, forms, personalized areas, and extensions that depend on changing session or request data. Clear the relevant Joomla cache after configuration changes when needed. Performance gains are useful only when the site continues to serve correct content.
Need More Help with Joomla?
Still having trouble? Open a support ticket with QuantaCade Support and we'll be happy to help where we can.
Support priority is given to QuantaCade products, services, and customers. However, we're also happy to assist fellow Joomla users with general Joomla questions and troubleshooting when possible.
QuantaCade is an independent Joomla extension developer and is not official Joomla support. Some issues involving third-party extensions, hosting environments, server configurations, or other systems outside our development control may be beyond what we're able to resolve.