Tags: performance

Performance is a high priority for me with The Session. It needs to work for people all over the world using all kinds of devices.

My main strategy for ensuring good performance is to diligently apply progressive enhancement. The core content is available to any device that can render HTML.

To keep things performant, I’ve avoided as many assets (or, more accurately, liabilities) as possible. No uneccessary images. No superfluous JavaScript libraries. Not even any web fonts (gasp!). And definitely no third-party resources.

The pay-off is a speedy site. If you want to see lab data, run a page from The Session through lighthouse. To see field data, take a look at data from Chrome UX Report (Crux).

But the devil is in the details. Even though most pages on The Session are speedy, the outliers have bothered me for a while.

Take a typical tune page on the site. The data is delivered from the server as HTML, which loads nice and quick. That data includes the notes for the tune settings, written in ABC notation, a nice lightweight text format.

Then the enhancement happens. Using Paul Rosen’s brilliant abcjs JavaScript library, those ABCs are converted into SVG sheetmusic.

So on tune pages there’s an additional download for that JavaScript library. That’s not so bad though—I’m using a service worker to cache that file so there’ll only ever be one initial network request.

If a tune has just a few different versions, the page remains nice and zippy. But if a tune has lots of settings, the computation starts to add up. Converting all those settings from ABC to SVG starts to take a cumulative toll on the main thread.

I pondered ways to avoid that conversion step. Was there some way of pre-generating the SVGs on the server rather than doing it all on the client?

In theory, yes. I could spin up a headless browser, run the JavaScript and take a snapshot. But that’s a bit beyond my backend programming skills, so I’ve taken a slightly different approach.

The first time anyone hits a tune page, the ABCs getting converted to SVGs as usual. But now there’s one additional step. I grab the generated markup and send it as an Ajax payload to an endpoint on my server. That endpoint stores the sheetmusic as a file in a cache.

Next time someone hits that page, there’s a server-side check to see if the sheetmusic has been cached. If it has, send that down the wire embedded directly in the HTML.

The idea is that over time, most of the sheetmusic on the site will transition from being generated in the browser to being stored on the server.

So far it’s working out well.

Take a really popular tune like The Lark In The Morning. There are twenty settings, and each one has four parts. Previously that would have resulted in a few seconds of parsing and rendering time on the main thread. Now everything is delivered up-front.

I’m not out of the woods. A page like that with lots of sheetmusic and plenty of comments is going to have a hefty page weight and a large DOM size. I’ve still got a fair bit of main-thread work happening, but now the bulk of it is style and layout, whereas previously I had the JavaScript overhead on top of that.

I’ll keep working on it. But overall, the speed improvement is great. A typical tune page is now very speedy indeed.

It’s like a microcosm of web performance in general: respect your users’ time, network connection and battery life. If that means shifting the work from the browser to the server, do it!

Web Summer Camp in Croatia finished with an interesting discussion. It was labelled a town-hall meeting, but it was more like an Oxford debating club.

Two speakers had two minutes each to speak for or against a particular statement. Their stances were assigned to them so they didn’t necessarily believe what they said.

One of the propositions was something like:

In the future, sustainable design will be as important as UX or performance.

That’s a tough one to argue against! But that’s what Sophia had to do.

She actually made a fairly compelling argument. She said that real impact isn’t going to come from individual websites changing their colour schemes. Real impact is going to come from making server farms run on renewable energy. She advocated for political action to change the system rather than having the responsibility heaped on the shoulders of the individuals making websites.

It’s a fair point. Much like the concept of a personal carbon footprint started life at BP to distract from corporate responsibility, perhaps we’re going to end up navel-gazing into our individual websites when we should be collectively lobbying for real change.

It’s akin to clicktivism—thinking you’re taking action by sharing something on social media, when real action requires hassling your political representative.

I’ve definitely seen some examples of performative sustainability on websites.

For example, at the start of this particular debate at Web Summer Camp we were shown a screenshot of a municipal website that has a toggle. The toggle supposedly enables a low-carbon mode. High resolution images are removed and for some reason the colour scheme goes grayscale. But even if those measures genuinely reduced energy consumption, it’s a bit late to enact them only after the toggle has been activated. Those hi-res images have already been downloaded by then.

Defaults matter. To be truly effective, the toggle needs to work the other way. Start in low-carbon mode, and only download the hi-res images when someone specifically requests them. (Hopefully browsers will implement prefers-reduced-data soon so that we can have our sustainable cake and eat it.)

Likewise I’ve seen statistics bandied about around the energy-savings that could be made if we used dark colour schemes. I’m sure the statistics are correct, but I’d like to see them presented side-by-side with, say, the energy impact of Google Tag Manager or React or any other wasteful dependencies that impact performance invisibly.

That’s the crux. Most of the important work around energy usage on websites is invisible. It’s the work done to not add more images, more JavaScript or more web fonts.

And it’s not just performance. I feel like the more important the work, the more likely it is to be invisible: privacy, security, accessibility …those matter enormously but you can’t see when a website is secure, or accessible, or not tracking you.

I suspect this is why those areas are all frustratingly under-resourced. Why pour time and effort into something you can’t point at?

Now that I think about it, this could explain the rise of web accessibility overlays. If you do the real work of actually making a website accessible, your work will be invisible. But if you slap an overlay on your website, it looks like you’re making a statement about how much you care about accessibility (even though the overlay is total shit and does more harm than good).

I suspect there might be a similar mindset at work when it comes to interface toggles for low-carbon mode. It might make you feel good. It might make you look good. But it’s a poor substitute for making your website carbon-neutral by default.

You can split the web in many ways. Lionel Dricot wrote about one of those ways in a blog post called Splitting the Web. In it, he outlines an ever-increasing divide he sees on the web.

On the one hand you’ve got people experiencing the advertising-driven, tracking-addicted big players who provide a bloated and buggy user experience.

On the hand, you’ve got the more tech-savvy users with tracking blockers (misleadingly called ad blockers) using browsers and search engines that value privacy and performance.

It feels like everyone is now choosing its side. You can’t stay in the middle anymore. You are either dedicating all your CPU cycles to run JavaScript tracking you or walking away from the big monopolies. You are either being paid to build huge advertising billboards on top of yet another framework or you are handcrafting HTML.

Maybe the web is not dying. Maybe the web is only splitting itself in two.

This reminded me of a post by Chris. No, not The Great Divide, although that’s obviously relevant here. Chris wrote a post just yesterday called Other People’s Busted Software is an Opportunity:

One way to look at it is opportunity. If you make software that does work reliably, you’ve got a leg up. Even if your customers don’t tell you “I like your software because it always works”, they’ll feel it and make choices around knowing it.

I like that optimistic take. If the majority seems to be doubling down on more tracking, more JavaScript, and more enshittification, then there’s a potential opportunity there (acknowledging that you’ve still got to battle against inertia and sunk cost).

This reminds of a fantastic talk that Stuart gave a few years ago called Privacy could be the next big thing:

How do you end up shaping the world? By inventing a thing that the current incumbents can’t compete against. By making privacy your core goal. Because companies who have built their whole business model on monetising your personal information cannot compete against that. They’d have to give up on everything that they are, which they can’t do. Facebook altering itself to ensure privacy for its users… wouldn’t exist. Can’t exist. That’s how you win.

Web performance is an unalloyed good. No one has ever complained that a website is too fast.

So the benefit is pretty obvious. Users like fast websites. But there are other benefits to web performance. And they don’t all get equal airtime.

Business

A lot of good web performance practices come down to the first half of Postel’s Law: be conservative in what send. Images, fonts, JavaScript …remove what you don’t need and optimise the hell out of what’s left.

That can translate to savings. If you’re paying for the bandwidth every time a hefty file is downloaded, your monthly bill could get pretty big.

So apart from the indirect business benefits of happy users converting to happy customers, there can be a real nuts’n’bolts bottom-line saving to be made by having a snappy website.

Sustainability

This is related to the cost-savings benefit. If you’re shipping less stuff down the wire, and you’re optimising what you do send, then there’s less energy required.

Whether less energy directly translates to a smaller carbon footprint depends on how the energy is being generated. If your servers are running on 100% renewable energy sources, then reducing the output of your responses won’t reduce your carbon footprint.

But there’s an energy cost at the other end too. Think of all the devices making requests to your server. If you’re making those devices work hard—by downloading, parsing, executing lots of JavaScript, for example—then you’re draining battery life. And you can’t guarantee that the battery will be replenished from renewable energy sources.

That’s why sites like the website carbon calculator have so much crossover with web performance:

From data centres to transmission networks to the billions of connected devices that we hold in our hands, it is all consuming electricity, and in turn producing carbon emissions equal to or greater than the global aviation industry. Yikes!

Inclusivity

There comes a point when a slow website isn’t just inconvenient, it’s inaccessible.

I’ve always liked the German phrase for accessible: barrierefrei—free of barriers. With every file you add to a website’s dependencies, you’re adding one more barrier. Eventually the barrier is insurmountable for people with older devices or slower internet connections. If they can no longer access your website, your website is quite literally inaccessible.

Making the case

I’ve noticed that when it comes to making the argument in favour of better web performance, people often default to the business benefits.

I get it. We’re always being told to speak the language of business. The psychology seems pretty straightforward; if you think that the people you’re trying to convince are mostly concerned with the bottom line, use the language of commerce to change their minds.

But that’s always felt reductive to me.

Sure, those people almost certainly do care about the business. Who doesn’t? But they’re also humans. I feel like if really want to convince them, speak to their hearts. Show them the bigger picture.

Eliel Saarinen said:

Always design a thing by considering it in its next larger context; a chair in a room, a room in a house, a house in an environment, an environment in a city plan.

I think the same could apply to making the case for web performance. Don’t stop at the obvious benefits. Go wider. Show the big-picture implications.