Combining load testing with application performance management is a great way to provide seamless IT management through the entire application delivery chain. Coupling load testing with application performance management in production is a the only way to deal with the current state of application complexity
In an ideal world, software professionals find and fix performance bottlenecks long before the application gets into users’ hands. But more often, performance testing happens after the fact, in response to user complaints that the software runs too slowly. “Developers are always surprised when they see how [poorly] their applications perform under load,” said J.P. Jackson, a project manager for the State of Michigan who oversees the performance of thousands of applications produced by a dozen different development teams across Michigan.
You can read more here: FAQ: Load testing software and application performance management