First off, I love Ruby and Clojure dearly.<p>However, the author justifies that Clojure was necessary because he only had 4 engineers and didn&#x27;t have time to scale Ruby, he just wanted something fast because he had to run too many servers.<p>I don&#x27;t buy it, unless your developers are free (highly unlikely).<p>The most expensive part of any tech startup is almost always developer time. AWS is pennies compared to how much it costs to learn a new tool&#x2F;language or iterate slower. Clojure is amazing, and I think times will change, but Rails + all the libraries are hugely faster for me to execute in than anything Clojure can do.<p>If I had a choice of paying another $10K to AWS or hiring a $150K&#x2F;year dev in the short term, guess which one I&#x27;m going to pick. You can buy <i>a lot</i> of cpu time for that, and hold on to that $140K.<p>The thing that kills startups is cash flow, not IO or perf.<p>Again, I love Clojure. But I have a really hard following this guy&#x27;s logic because 99% of startups don&#x27;t need their boxes to go 10x faster, they need $$$ for runway.