I'd caution that the people not familiar with working at the low level are often missing a bunch of associated knowledge which is useful in the day to day.

You run into Python/Javascript/etc programers who have no concept of what operations might execute quickly or slowly. There isn't a mental model of what the interpreter is doing.

We're often insulated from the problem because the older generation often used fairly low level languages on very limited computers, and remember lessons from that era. That's not true of younger developers.

Depends on the operation tbh, and whether the one or the other is a micro-optimization or actually significant. It's better to focus on high-level optimizations, core architecture decisions and the right algorithms than on an operation level. Unless those operations are executed billions of times and the difference becomes statistically significant, of course.