I was skeptical given the title that the article could defend it's claim, but the article was strong and made great points. The only thing I would add (which I

I was skeptical given the title that the article could defend it's claim, but the article was strong and made great points. The only thing I would add (which I concur probably doesn't belong in the article itself): Most databases make it trivial to see how long your queries are taking. Use that to help you identify the performance bottlenecks! If a request/response cycle takes 200 ms from the entrypoint of your rails server, and the database query reported (from the db) took 1 ms, that's a whole lot different than if the db query took 150 ms. On scaling in general, in my experience inefficient queries are the vast majority of performance problems for most apps. It's usually fairly easy to identify these as different endpoint will perform very differently so you can get an idea of the baseline and identify aberrations. If that's happening then check your queries. If the whole app (baseline) is slow, TFA has phenonmenal guidance.