Until your app gets on HN/Slashdot/Reddit etc and experiences the hug of death. Jokes aside, I do agree that from a developer's standpoint, the optimal way to

Until your app gets on HN/Slashdot/Reddit etc and experiences the hug of death. Jokes aside, I do agree that from a developer's standpoint, the optimal way to act (optimising for business success) is as you say, ignore performance at first. But from an engineering/craftsmanship standpoint, it should really bother you to have an inefficient system. Just think of all that extra CPU load, and all the CO2, all the coal burnt to sustain it ...