Tags: performance

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Redux: Lazy loading youtube embeds

Remy has an excellent improvement on that article I linked to yesterday on using srcdoc with iframes. Rather than using srcdoc instead of src, you can use srcdoc as well as src. That way you can support older browsers too!

Time to First Byte: What It Is and Why It Matters by Harry Roberts

Harry takes a deep dive into the performance metric of “time to first byte”, or TTFB if you using initialisms that take as long to say as the thing they’re abbreviating.

This makes a great companion piece to Drew’s article on server timing headers.

Lazy load embedded YouTube videos - DEV Community 👩‍💻👨‍💻

This is a clever use of the srcdoc attribute on iframes.

Native lazy-loading for the web  |  web.dev

The title is somewhat misleading—currently it’s about native lazy-loading for Chrome, which is not (yet) the web.

I’ve just been adding loading="lazy" to most of the iframes and many of the images on adactio.com, and it’s working a treat …in Chrome.

Don’t build that app! – Luke Jackson - YouTube

This is a fascinating look at how you can get the benefits of React and npm without using React and npm.

Here’s an accompanying article on the same topic.

How to test vanilla JS performance | Go Make Things

Did you know about console.time() and console.timeEnd()? I did not.

Fast Software, the Best Software — by Craig Mod

Fast software is not always good software, but slow software is rarely able to rise to greatness. Fast software gives the user a chance to “meld” with its toolset. That is, not break flow.

The Simplest Way to Load CSS Asynchronously | Filament Group, Inc.

Scott re-examines the browser support for loading everything-but-the-critical-CSS asynchronously and finds that it might now be as straightforward as this one declaration:

<link rel="stylesheet" href="/path/to/my.css" media="print" onload="this.media='all'">

I love the fact the Filament Group are actively looking at how deprecate their loadCSS polyfill—exactly the right attitude for polyfills in general.

How Google Pagespeed works: Improve Your Score and Search Engine Ranking

Ben shares the secret of SEO. Spoiler: the villain turns out to be Too Much JavaScript. Again.

Time to Interactive (TTI) is the most impactful metric to your performance score.

Therefore, to receive a high PageSpeed score, you will need a speedy TTI measurement.

At a high level, there are two significant factors that hugely influence TTI:

  • The amount of JavaScript delivered to the page
  • The run time of JavaScript tasks on the main thread

The Crushing Weight of the Facepile—zachleat.com

Using IntersectionObserver to lazy load images—very handy for webmention avatars.

When should you be using Web Workers? — DasSur.ma

Although this piece is ostensibly about why we should be using web workers more, there’s a much, much bigger point about the growing power gap between the devices we developers use and the typical device used by the rest of the planet.

While we are getting faster flagship phones every cycle, the vast majority of people can’t afford these. The more affordable phones are stuck in the past and have highly fluctuating performance metrics. These low-end phones will mostly likely be used by the massive number of people coming online in the next couple of years. The gap between the fastest and the slowest phone is getting wider, and the median is going down.

Designing for actual performance by Adam Silver

This is something I’ve been thinking about a lot lately. The justification for single page apps feels like circular thinking to me. A JavaScript framework is needed to avoid full page refreshes because full page refreshes are expensive because that means assets will be reloaded …assets like the JavaScript framework that only exists to avoid the full page refresh.

This is how it goes. We put a load of shit into a single web page. This makes the page slow. Slow to load, slow to render. Slow.

Instead of getting rid of the shit, we blame the page refresh.

Self-Host Your Static Assets – CSS Wizardry

Trust no one! Harry enumerates the reason why you should be self-hosting your assets (and busts some myths along the way).

There really is very little reason to leave your static assets on anyone else’s infrastructure. The perceived benefits are often a myth, and even if they weren’t, the trade-offs simply aren’t worth it. Loading assets from multiple origins is demonstrably slower.

Characteristics of a Strong Performance Culture | TimKadlec.com

Tim looks at the common traits of companies that have built a good culture of web performance:

  1. Top-down support
  2. Data-driven
  3. Clear targets
  4. Automation
  5. Knowledge sharing
  6. Culture of experimentation
  7. User focused, not tool focused

Few companies carry all of these characteristics, so it’s important not to get discouraged if you feel you’re missing a few of them. It’s a process and not a quick one. When I’ve asked folks at companies with all or most of these characteristics how long it took them to get to that point, the answer is typically in years, rarely months. Making meaningful changes to culture is much slower and far more difficult than making technical changes, but absolutely critical if you want those technical changes to have the impact you’re hoping for.

Web Bloat Score Calculator

Page web bloat score (WebBS for short) is calculated as follows:

WebBS = TotalPageSize / PageImageSize

Yes, this is a tongue-in-cheek somewhat arbitrary measurement, but it’s well worth reading through the rationale for it.

How can the image of a page be smaller than the page itself?

Test the impact of ads and third party scripts

This is a very useful new feature in Calibre, the performance monitoring tool. Now you can get data about just how much third-party scripts are affecting your site’s performance:

The best way of circumventing fear and anxiety around third party script performance is to capture metrics that clearly articulate their performance impact.

Progressive Font Enrichment: reinventing web font performance | Responsive Web Typography

Jason describes the next big thing in web typography: streaming fonts!

…to enable the ability for only the required part of the font be downloaded on any given page, and for subsequent requests for that font to dynamically ‘patch’ the original download with additional sets of glyphs as required on successive page views—even if they occur on separate sites.

How I failed the <a>

I think the situation that Remy outlines here is quite common (in client-rehydrated server-rendered pages), but what’s less common is Remy’s questioning and iteration.

So I now have a simple rule of thumb: if there’s an onClick, there’s got to be an anchor around the component.

Preload, prefetch and other link tags: what they do and when to use them · PerfPerfPerf

Following on from Harry’s slides, here’s another round-up of thoserel attribute values that begin with pre.

More Than You Ever Wanted to Know About Resource Hints - Speaker Deck

Slides from Harry’s deep dive into rel values: preconnect, prefetch, and preload.