Application performance management (APM) isn't just for system administrators. It can and should be an integral part of the software development cycle. Some problems show up only after running for a long period of time, and APM is one of the best ways to make developers aware of them. Not every bug immediately produces incorrect results. Some of them make the application slow down over time. Some make it crash after a long period or when an unusual situation occurs. Code which works well with test data may not scale well as its database grows. Normal testing won't always catch these issues.
