You will learn many things from this book, including the following:
What the various performance tools measure
How to use each tool
How to combine the tools to solve a performance problem
How to start with a poorly performing system and pinpoint the problem
How the methods are used to solve real-world problems (case studies)
Using the methods in this book, you can make a well-organized and diagnosed problem description that you can pass on to the original developers. If you're lucky, they will solve the problem for you.