> And, code performance is, as you say, part of test performance. If the tests take too long, perhaps the code needs to be improved.

Yes. I mentioned this is in the last section. When test-performance is alright, typically you don't need to optimize code anymore.

For me, optimizations in the "code performance" category are for example trading off a generalist API for a more complicated tweaked version that reaches into details and enables caching. The kinds of optimizations game developers do where they make the code less general and pretty, but more performant.

> OTOH, I have got a few test suites that run for 30 minutes or more, just because the search space is so big. But that's code that only needs to be tested once.

What are these suites testing?