There are several caching plugins you can use for your WordPress sites, which can help to improve your website load time and overall performance. They can also help your site to handle large spikes in traffic like the Slashdot effect. The following is a general overview of recommended plugins you can use on DreamHost's servers:
WP Super Cache
WP Super Cache creates a static file cache of your site and loads that instead of using PHP to generate the page. Picking up where WP-Cache left off, this plugin includes advanced features as well as a plugin and hooks system. WP Super Cache is included with all new deluxe One-Click Installs of WordPress from the DreamHost web panel. If you're on shared hosting, this is the best option.
See the following article for more information on setting up WP Super Cache:
Hyper Cache is an effective and user-friendly caching plugin and is an outstanding alternative for most WordPress users.
DreamPress uses Varnish Caching and Memcached, along with pre-installed plugins that are specifically configured to help WordPress take full advantage of these features. There is no need for DreamPress users to install any caching plugins.