My main point here is, that while one can work hard to try and tune Rails (Shopify's done it, Stripe's done it) - and I would argue that it's more of an effort than some DevOps personnel updating a pod count - it's fairly easy to start with something that is already very performant. SpringBoot is an opinionated framework for Java that has very good raw performance. I'm simply advocating that it doesn't hurt to start with something that's already pretty good. That's not premature optimization, it's just making wise decisions from the start.