[jacquesm]

> One lesson to take from this is that it's often worth spending an extra half hour or hour validating that your assumptions about where time is being spent are true.

That is the real takeaway from the article.

Making assumptions is fine, making assumptions and not immediately verifying whether they hold or not is not.

This is why it is super important to actually write down your assumptions and test them one-by-one when implementing some solution. More often than not you'll find that there is some light between what you thought was true and what is really happening.

So this is much more a systemic problem than just a database tuning problem.