PHP applications are becoming more complex than ever before. We've moved away from the simple LAMP stack to having many different layers and pieces that our application interacts with. There are many places where things can slow down or break. We'll discuss the different parts of a PHP application including the browser, php application, database, and the server. We'll show different tools for each part and how to use them. By the end of this presentation you should have a whole arsenal of tools to help you profile & understand your application much better.