How well do you know the tools you use?

Last week, while working on an app that uses React, I found what I thought was a legitimate reason to use the `useMemo` hook. However, using it triggered a bigger conversation about performance optimizations and made me question why I use the tools I do. My usage of it was the first time it appeared in our codebase at work. A colleague noted that he'd been meaning to use too but presumably never found a good opportunity. I half-jokingly said that it'd been almost two years since I first learned about `useMemo` to have a valid(ish) use case, despite its popularity as a React interview question. However, using it triggered a broader conversation about React performance optimizations in our codebase. It started with whether (and where) `useMemo` can be useful or not and expanded to include the bigger picture question of which optimizations are worth pursuing. ## Know your tools For a good reason, it's often said that a software engineer's job is to pick the right tool for the job. As a new developer, I often heard that a cardinal sin of juniors is that they use the one tool they learned from everything, without asking whether it's the right one. I wanted to avoid that, but ran into a different kind of issue. During review, our founder did a deeper dive into `useMemo` and found a [well-argued article](https://medium.com/swlh/should-you-use-usememo-in-react-a-benchmarked-analysis-159faf6609b7) that benchmarks its performance. This part struck me: > If we look at the [React documentation regarding useMemo](https://reactjs.org/docs/hooks-reference.html#usememo) it is not mentioned when it should be used. They simply mention what it does and how it can be used. \[…] > > The question here is, from what point on is useMemo interesting? How complex or big should the data be before we see performance advantages in using useMemo? When should developers actually use useMemo? — Kevin Van Ryckegem That point struck home. I forgot to consider that aspect. I was aware that React doesn't prescribe usage on purpose, leaving many decisions (and possible pitfalls) up to the user. Using was valid, according to the definition. But the point is, I didn't *know* for sure. That question was an a-ha moment: I based my usage of `useMemo` on a vague sense of social proof that *" the smart people at React say it's good for this use case, so it must be"*. ## Develop deliberately In hindsight, I wish I'd been more deliberate about it. But the whole discussion reinforced the importance of knowing which tools you use, and why. If I can't articulate a good reason why one tool or solution is better than other, that should be a sign to either not use it, or be upfront about shortcuts and assumptions and dig deeper. So in that sense, our founder set a great example with the research. Looking for examples and discussing them with others created both a learning opportunity for me, and enriched our perspectives as they related to the challenge at hand. Sometimes, a shortcut is the longest distance between two points. But this detour was worth it.