(Quick Reference)
Purpose
This tag allows you to cache a section of content within a Template or Widget, so that it is not executed again for a certain period of time. The content is also rendered into the page, but in future it will come from the cache until the cache expires.
If you are processing intensive data access within a page, such as retrieving content from a remote service or iterating over many content nodes with eachChild for example, then wrapping this in a cache tag will greatly improve performance.
Example
<!-- Caching with no key attribute caches the content only for the current request URI -->
<wcm:cache>
This will be cached
<g:each in="${(5..10)}">This will be executed only when the cache needs refreshing</g:each>
</wcm:cache><!-- This uses a specific key so that this shared block can be used across different pages -->
<wcm:cache key="shared-feed-info">
Some code here to get a feed from a remote site
</wcm:cache><!-- Caching with a name attribute selects a different cache -->
<wcm:cache name="yourCustomEhCache">
This will be cached
</wcm:cache>The default cache is "contentCache" and currently has a time to live of 1 hour. During development in non-production environments you can force a refresh of the cache by adding a "refresh" parameter to your URL.