In theory, customers should be able to feel the software performance improvements from first-hand experience.

In practice, sometimes the improvements are not noticible enough, such that in order to monetize from the improvements, it is necessary to use quotable performance figures in marketing in order to attract customers.

We already know the difference between perceived performance (GUI latency, etc) and server-side performance (machines, networks, infrastructure, etc).

How often is it that programmers need to go the extra length to "write up" performance analyses for which the audience is not fellow programmers, but managers and customers?