I think a lot of people (especially those who are only peripherally involved in development, like management) don't really consider performance regressions at all when thinking about how to get software to go faster.

Meanwhile my experience has been that whenever there has been a performance issue severe enough to actually matter, it's often been the result of some kind of performance bug, not so much language, runtime, or even algorithm choices for that matter.

Hence whenever the topic of how to improve performance comes up, I always, always insist that we profile first.