Testing or engineering?
If performance testing were only about testing, strictly as the name says, than we could limit ourselves to check the response times against some sort of yardstick, a norm or standard, at the prescribed transaction volume and decide if they take longer or shorter. As a result we would document this in a concise report. Imagine that you after a performance test tell your customer: “I have tested your application and have finished now. The transaction types with the numbers 3, 12 and 17 have response times that are OK, but the other 47 transactions of your application do not meet their requirements. Good luck!” Though quite common in functional testing, this sounds pretty ridiculous to me.
Performance testing without performance engineering is like a pub without beer!
As if by nature, a performance tester gathers application intelligence, which is another interesting phenomenon (I will discuss in a future blog) and hand it over to the software developers.