A P P E N D I X B
Profiling Drupal and Optimizing Performance
You don't usually need to worry about performance when developing Drupal sites and modules; instead, you should focus on clean, functional design and readability of your code. However, if your site experiences more traffic than usual or it somehow feels slow, there are ways to analyze and improve the situation.
When it comes to web sites, the perceived performance is key to user acceptance. In the words of Roy T. Fielding, a central figure in defining the modern web's architecture, user-perceived performance ...