Read the Tea Leaves Software and other dark arts, by Nolan Lawson

Every so often, I come across a web performance post from what I like to call the “one weird trick” genre. It goes something like this:

“I improved my page load time by 50% by adding one line of CSS!”

or

“It’s 2x faster to use this JavaScript API than this other one!”

The thing is, I love a good performance post. I love when someone finds some odd little unexplored corner of browser performance and shines a light on it. It might actually provide some good data that can influence framework authors, library developers, and even browser vendors to improve their performance.

But more often than not, the “one weird trick” genre drives me nuts, because of what’s not included in the post:

• Did you test on multiple browsers?
• Did you profile to try to understand why something is slower or faster?
• Did you publish your benchmark so that others can verify your results?

That’s why I wrote “How to write about web performance”, where I tried to summarize everything that I think makes for a great web perf post. But of course, not everyone reads my blog religiously (how dare they?), so the “one weird trick” genre continues unabated.

Look, I get it. Writing about performance is hard. And we’re not all experts. I’ve made the same mistakes myself, in posts like “High performance web worker messages” (2016) – where I found the “one weird trick” that it’s faster to stringify an object before sending it to a web worker. Of course this makes little sense (the browser should be able to serialize the object faster than you can do it yourself), and Surma has demonstrated that there’s no need to do this stringify dance in modern versions of Chrome. (As I’ve said before: if you’re not wrong about web perf today, you’ll be wrong tomorrow when browsers change!)

That said, I do occasionally find a post that really exemplifies what’s great about the web perf genre. For instance, this post by Eoin Hennessy about improving Webpack performance really ticks all the boxes. The author wasn’t satisfied with finding “one weird trick” – they had to understand why the trick worked. So they actually went to the trouble of building Node from source (!) to find the true root cause, and they even submitted a patch to Webpack to fix it.

A post like this, like a good mystery novel, has everything that makes for a satisfying story: the problem, the search, the resolution, the ending. Unlike the “one weird trick” posts, this one doesn’t leave me craving more. Instead, it leaves me feeling like I truly learned something about how browser engines work.

So if you’ve found “one weird trick,” that’s great! There might actually be something really interesting there. But unless you do the extra research, it’s hard to say more than just “Well, this technique worked for me, on my website, in Chrome, in this scenario…” (etc.). If you want to extrapolate from your results to something more widely-applicable, you have to put in the work.

So here are some things you can do. Test in multiple browsers. File a browser bug if one is slower than the others. Ask around if you know any web perf experts or folks who work at browser vendors. Take a performance profile. And if you put in just a bit of extra effort, you might find more than “one weird trick” – you might find a valuable learning opportunity for web developers, browser vendors, or anyone interested in how the web works.