The top four web performance challenges

  • time to first render,
  • time to first meaningful paint, or
  • time to first meaningful interaction.
  • number of requests, or
  • pagespeed insights score.

4. Web fonts

Coming in at number four, it’s web fonts. Sometimes it’s the combined weight of multiple font files that’s the problem, but more often that not, it’s the perceived performance that suffers (mostly because of when the web fonts appear).

3. Images

At the number three spot, it’s images. There are more of them and they just seem to be getting bigger all the time. And yet, we have more tools at our disposal than ever — better file formats, and excellent browser support for responsive images. Heck, we’re even getting the ability to lazy load images in HTML now.

2. Our JavaScript

Just missing out on making the top spot is the JavaScript that we send down the pipe to our long-suffering users. There’s nothing wrong with the code itself — I’m sure it’s very good. There’s just too damn much of it. And that’s a real performance bottleneck, especially on mobile.

1. Other people’s JavaScript

At number one with a bullet, it’s all the crap that someone else tells us to put on our websites. Analytics. Ads. Trackers. Beacons. “It’s just one little script”, they say. And then that one little script calls in another, and another, and another.

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Jeremy Keith

Jeremy Keith

A web developer and author living and working in Brighton, England. Everything I post on Medium is a copy — the originals are on my own website, adactio.com