The first thing to cover here is “Why are we doing all this?” and the answer is to satisfy a service level agreement (SLA) we have made with our clients or end users. There are arguments that say the benefits of application performance management (APM) are outweighed by the costs, which we address boldly up front.
There is also a possible return on investment (ROI) in managing performance:
The ROI of Application Performance Management
This paper offers “examples and simple calculations [that] can provide a starting point in building a business case for an application performance ...