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Page cache
Enabling the page cache will offer a significant performance boost. Drupal can store and send compressed cached pages requested by anonymous users. By caching a web page, Drupal does not have to construct the page each time it is viewed.

The normal cache mode is suitable for most sites and does not cause any side effects. The aggressive cache mode causes Drupal to skip the loading (boot) and unloading (exit) of enabled modules when serving a cached page. This results in an additional performance boost but can cause unwanted side effects.

The following enabled modules are incompatible with aggressive mode caching and will not function properly: admin_menu, uc_cart, uc_credit, uc_store.

On high-traffic sites, it may be necessary to enforce a minimum cache lifetime. The minimum cache lifetime is the minimum amount of time that will elapse before the cache is emptied and recreated, and is applied to both page and block caches. A larger minimum cache lifetime offers better performance, but users will not see new content for a longer period of time.
By default, Drupal compresses the pages it caches in order to save bandwidth and improve download times. This option should be disabled when using a webserver that performs compression.
Block cache
Enabling the block cache can offer a performance increase for all users by preventing blocks from being reconstructed on each page load. If the page cache is also enabled, performance increases from enabling the block cache will mainly benefit authenticated users.
Note that block caching is inactive when modules defining content access restrictions are enabled.
Bandwidth optimizations

Drupal can automatically optimize external resources like CSS and JavaScript, which can reduce both the size and number of requests made to your website. CSS files can be aggregated and compressed into a single file, while JavaScript files are aggregated (but not compressed). These optional optimizations may reduce server load, bandwidth requirements, and page loading times.

These options are disabled if you have not set up your files directory, or if your download method is set to private.

This option can interfere with theme development and should only be enabled in a production environment.
This option can interfere with module development and should only be enabled in a production environment.
Clear cached data
Caching data improves performance, but may cause problems while troubleshooting new modules, themes, or translations, if outdated information has been cached. To refresh all cached data on your site, click the button below. Warning: high-traffic sites will experience performance slowdowns while cached data is rebuilt.