I just wanted to jump in here and offer an unusual case where....
*THE CUSTOMERS FREAKING CARE ABOUT PERFORMANCE AND NOTICE EVERY LITTLE CHANGE!.
It's in my field where we cover production rendering which tends to be analyzed to death in terms of performance by the customers themselves. A 2% slowdown in performance over a minor version can equate to the slowdowns being reported in the form of "bug reports" en masse.
Forum threads are often started with customers benchmarking their scenes against various versions of the software, where the customers are actually benchmarking more than the developers themselves. "This scene took 1 hour and 40 minutes to render in version X. It now takes 32 minutes in version Y."
"This scene took 18 minutes to load in version X, now it takes 4 minutes to load in version Y."
They're extremely appreciative when optimizations are applied, and that alone may suffice to warrant a purchase of a new, very expensive upgrade of the software, and sometimes with only modest improvements like a 10% reduction in times.
In some larger contexts, it may also save the customer enormous amounts of money when the product is sped up, since some bigger studios use render farms where they have to pay for hundreds of machines rendering all day long, and any improvement in times here can speed up their whole production process (and possibly even yield better results when artists are more productive creating art rather than waiting for it to render).
So there exist fields like this where the customers really, really, really notice -- sometimes even more than the developers themselves, and this is outside of UI interaction concepts which are more about latency than throughput.
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?
In our case, all the time, with just about every minor release. Speed is one of the top selling points, and even the most technical benchmarks and performance analyses are actually appreciated and understood by the customers and managers. The perception of customers is often like rabid wolves, hungry for more optimizations, and trying to make suggestions to the developers about how to potentially make things go faster. In this case, it actually takes discipline to resist some of the customer urges to optimize further and focus on other metrics like maintainability and feature enhancements.