Internal Page Cache

Drupal 8 uses the Internal Page Cache module, which is recommended for small to medium-sized sites. This core module, enabled by default, caches pages for anonymous users. It can be found in core/modules/page_cache.

This feature enhances performance by speeding up the site. Pages requested by anonymous users are stored on first load and reused afterward; depending on your site configuration, the performance improvement can be significant.

To speed up your site for authenticated users, consider the Dynamic Page Cache module.

Websites that serve personalized content to anonymous users (session-based, such as a shopping cart) may want to disable the Internal Page Cache module. This module assumes that pages are identical for all anonymous users. These sites may still use the Dynamic Page Cache module or alternatively implement personalization using JavaScript + AJAX.

Configuring the Internal Page Cache Module

On the Performance page (admin/config/development/performance), you can define how long browsers and proxies may cache pages. No other configuration is available. The setting for maximum page caching time by browsers and proxies affects the Cache-Control headers. However, the Internal Page Cache itself ignores this setting and caches pages until they become invalid unless they include an Expires header.

Comparison with Drupal 7

1. Drupal 7 lacks instant updates; in Drupal 8, the page cache is immediately updated when something changes.
2. Drupal 7 required clearing the entire page cache when content changed; Drupal 8 uses cache tags to invalidate only cached pages that depend on the modified content.
3. Drupal 7 often displayed outdated pages, as no module (not even core ones) could reliably invalidate the page cache.
4. Drupal 7 did not enable internal page caching by default. Many users didn’t realize they needed to enable it. Drupal 8 enables page caching for anonymous users by default, thanks to cache tags. Enabling it by default in Drupal 7 would have caused issues due to the lack of cache tags.

See Also

• Drupal 8 now has page caching enabled by default
• Developer documentation on Cache Tags