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Writing performant code by using the correct idioms, data structures, algorithms, etc, from the start is just common sense rather than 'premature optimisation'.

Writing unreadable, micro-optimised code in the name of performance without even attempting to profile it first is another matter.

My personal rule (as a not-very-good hobbyist) is that if I have to refactor everything in order to accommodate an optimisation in a path that's already 'fast enough', or introduce some arcane hackery that only makes sense with comments into otherwise clean code, then it must be backed up with realistic benchmarks (and show a significant improvement).