For most developers performance testing sounds like something really difficult to get started on. It might come to mind that some special and usually expensive environment and tools to test the performance.
Well, sometimes you do indeed need them to test the network communications impact, or if you have a cluster and want to measure its capacity, for example. But if you have some small system or you don’t have a lot of money, you may still face performance problems. Sometimes you can’t scale the environment, because it is expensive or your code has bugs preventing it from scaling.