Performance testing and objectives
There's no denying the importance of a performance test campaign in the quality assurance process. But I have lost count of customers requesting load test with no specific objective (or just "improve the performance"). Running a test campaign with no objective in mind is quite risky. You might spend a lot of efforts on useless improvements whereas the critical pain points remain.
Endless tuning
I worked on performance campaigns with no objective defined a couple of times. Usually, this implies running tests until you run out of time/budget and optimizing whatever you can. It does not mean these campaigns were not successful, but they probably cost a lot more money than they should have.