Well, can we really call it premature optimization if it's needed?
Reminds me of using Ruby ten years ago and having to contend with folks who wanted to default to using the string literal style over another because it was known to be more performant at scale. That awkward stuff surfaces earlier with some languages than with others.
I guess if folks write JS with the idea that optimisations are needed in mind, then the chances of premature optimisations may go up along with those of the required ones