Fragment Caching with Rails 5.1

I cover all in depth in my Ruby on Rails 5.1 book. In this post I’d like to give a quick overview of Fragment Caching which is the most used caching method. Often it is the lowest hanging fruit. But I’ve seen plenty of Rails projects where it was used in a way that it actually decreased the speed. Most times because of too long and too complicated cache keys. In those cases it takes more time to calculate the cache key than it would take to render the content of the cache.