It is very easy to write code that “works on my machine” or “works in QA” and then fails when it hits production volumes or a requirement changes to add more us

It is very easy to write code that “works on my machine” or “works in QA” and then fails when it hits production volumes or a requirement changes to add more users/elements. Then it often becomes prohibitively expensive to just throw more servers/VMs at it. And often the “expensive” engineer changing a nested loop into a map lookup can save years of compute time in a matter of hours. Unfortunately all too often that only happens after scaling up/out without understanding why systems are slow. Don’t get me wrong, I’m not arguing for needless early optimisation but an inefficient query/algorithm can waste a lot of computing resources...