I have been working with Marco Villegas on a Project for Pega Systems (https://www.pega.com/). We are importing documentation into Drupal from an external system. The documentation is organized in Drupal using the core Book module, and some of the books have thousands of pages. The problem is that processing the navigation menu for such a large book takes a lot of time, on the order of a minute! I will describe how we leveraged the advanced caching system in Drupal 8 so that pages load in a reasonable amount of time without having to cache gigabytes of data.