Application performance has always been one of the pain points when performing development with Drupal, and there are many reasons for this. For example, PHP is not the fastest language out there. Many beginner Drupal developers fell pray to the multitude of modules available and go a bit overboard with enabling more than needed. Indeed, the Drupal architecture is simply not the most performant. In its defense though,it is a very complex architecture that does a lot out of the box will have some speed trade-offs.
One critical component in this game, however, is caching. For those of you not familiar with this term, caching is the application strategy of storing copies of processed code (or anything that results from it) in view of delivering it faster to the user when requested subsequent times. For example, when you go to a website, you browser is most likely going to...
