If your site mostly has anonymous (i.e. not logged-in) viewers, and you’re in a hosting environment where your pages are loading slowly, the Boost module may be a useful approach to improving performance. Usually, when a Drupal page loads, Drupal has to send many queries to its database and process the results into the page that people see. Boost provides static page caching -- in essence, saving the results from all those database queries into a page that can simply load, without having to interact with the database on the way.