To tune the performance of a system means to improve one or more of its measures of performance. The question is how, when, and where should it be done? This is an area of great underestimation and major misconception. In the subsections that follow, we'll give you some examples of common mistakes and problems. Try to avoid them, or help out by correcting them, whenever and wherever you can.
For many not-so-developed or understaffed organizations, performance testing with some possible tuning is more or less a one-off, something done just before an application is shipped out to production.
By only performing the testing and tuning at this point, the amount of work, if done properly, is much higher and much more complex than if it was done iteratively during the development of the application.
Naturally, an organization must keep within its financial limits, but doing performance testing just before a release is very hazardous. What will happen if an application turns out to not live up to the expected and necessary measures in production? It would clearly be very bad for business.
Very often, performance testing and tuning is run by staff that lacks the knowledge of how this testing and tuning should be performed. Getting the right individuals, in terms of competence, on board in the testing and tuning team is crucial. This can vary but normally involves quality assurance (QA) staff, experienced performance testers, and technical staff, such as architects and developers that have actually been involved in creating the system under test.
Even though the quality value of a system's performance has grown to be relatively recognized in most organizations today, there are still places where staff responsible for performance-related tests and tuning lack the voice or mandate to enforce proper quality tall-gates.
As passionate developers, we like to be clever. Making our code run smoothly is satisfying, and the performance improvements we make can give us a feel-good boost and self-confidence. That is great, but it's often not very meaningful to just (over)optimize our own functions or components. As developers, we won't know for sure how much or what parts of our code will actually be executed in such an amount that it will need performance tuning. In the long run, it can even hamper the performance as our optimizations might cause problems in other places of the system as a whole.
So, performance tuning is something that an organization as a whole should take seriously. It should be done iteratively and handled by a competent team with complementing skills, experiences, and mandate. As it's such an important factor for today's businesses, it should have a given place in any organizational process map.