High performance sites are hard to build with Drupal and in a number of cases the internal caching does not give enough boost. Exove has been working for years with all kinds of sites with extremely high performance requirements. We have developed a number of strategies and in this session we explore one of the most efficient one -- using external caching.

For that purpose, we have developed a specific Drupal module. Cache Control integrates sites with the Varnish HTTP accelerator -- and other external HTTP caches -- in a fashion that not only allows for caching page loads for anonymous users but also for authenticated users.

In this session, we briefly discuss how the module works and what are its benefits and limitations. Further, we discuss three real-life cases with high performance requirements that we solved using Cache Control. For all cases we describe how the module worked and what kind of problems we faced.

The first case is a happy case: a high-traffic site where administrators are the only authenticated users. Cache Control suits perfectly for this kind of case. The second case is different: A site where majority of users are authenticated, generate lots of content (making cache purging an issue) and the site shows a lot of personalized content. Cache Control works also in this kind of environment, but faces a lot of challenges. The third case is about dealing with geographical distribution rather than high traffic: We will discuss how Cache Control plays with Fastly CDN.