Tags: performance

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Tuesday, November 13th, 2018

Optimise without a face

I’ve been playing around with the newly-released Squoosh, the spiritual successor to Jake’s SVGOMG. You can drag images into the browser window, and eyeball the changes that any optimisations might make.

On a project that Cassie is working on, it worked really well for optimising some JPEGs. But there were a few images that would require a bit more fine-grained control of the optimisations. Specifically, pictures with human faces in them.

I’ve written about this before. If there’s a human face in image, I open that image in a graphics editing tool like Photoshop, select everything but the face, and add a bit of blur. Because humans are hard-wired to focus on faces, we’ll notice any jaggy artifacts on a face, but we’re far less likely to notice jagginess in background imagery: walls, materials, clothing, etc.

On the face of it (hah!), a browser-based tool like Squoosh wouldn’t be able to optimise for faces, but then Cassie pointed out something really interesting…

When we were both at FFConf on Friday, there was a great talk by Eleanor Haproff on machine learning with JavaScript. It turns out there are plenty of smart toolkits out there, and one of them is facial recognition. So I wonder if it’s possible to build an in-browser tool with this workflow:

  • Drag or upload an image into the browser window,
  • A facial recognition algorithm finds any faces in the image,
  • Those portions of the image remain crisp,
  • The rest of the image gets a slight blur,
  • Download the optimised image.

Maybe the selecting/blurring part would need canvas? I don’t know.

Anyway, I thought this was a brilliant bit of synthesis from Cassie, and now I’ve got two questions:

  1. Does this exist yet? And, if not,
  2. Does anyone want to try building it?

Inlining or Caching? Both Please! | Filament Group, Inc., Boston, MA

This just blew my mind! A fiendishly clever pattern that allows you to inline resources (like critical CSS) and cache that same content for later retrieval by a service worker.

Crazy clever!

Monday, November 12th, 2018

Squoosh

A handy in-browser image compression tool. Drag, drop, tweak, and export.

Home  |  web.dev

I guess this domain name is why our local developmemnt environments stopped working.

Anyway, it’s a web interface onto Lighthouse (note that it has the same bugs as the version of Lighthouse in Chrome). Kind of like webhint.io.

Saturday, November 10th, 2018

CSS and Network Performance – CSS Wizardry

Harry takes a look at the performance implications of loading CSS. To be clear, this is not about the performance of CSS selectors or ordering (which really doesn’t make any difference at this point), but rather it’s about the different ways of getting rid of as much render-blocking CSS as possible.

…a good rule of thumb to remember is that your page will only render as quickly as your slowest stylesheet.

Thursday, November 8th, 2018

Designing, laws, and attitudes. — Ethan Marcotte

Ethan ponders what the web might be like if the kind of legal sticks that exist for accessibility in some countries also existed for performance.

Sunday, October 28th, 2018

The Three Types of Performance Testing – CSS Wizardry

Harry divides his web performance work into three categories:

  1. Proactive
  2. Reactive
  3. Passive

I feel like a lot of businesses are still unsure where to even start when it comes to performance monitoring, and as such, they never do. By demystifying it and breaking it down into three clear categories, each with their own distinct time, place, and purpose, it immediately takes a lot of the effort away from them: rather than worrying what their strategy should be, they now simply need to ask ‘Do we have one?’

Tuesday, October 9th, 2018

AddyOsmani.com - Start Performance Budgeting

Great ideas from Addy on where to start with creating a performance budget that can act as a red line you don’t want to cross.

If it’s worth getting fast, it’s worth staying fast.

Monday, October 8th, 2018

The Hurricane Web | Max Böck - Frontend Web Developer

When a storm comes, some of the big news sites like CNN and NPR strip down to a zippy performant text-only version that delivers the content without the bells and whistles.

I’d argue though that in some aspects, they are actually better than the original.

The numbers:

The “full” NPR site in comparison takes ~114 requests and weighs close to 3MB on average. Time to first paint is around 20 seconds on slow connections. It includes ads, analytics, tracking scripts and social media widgets.

Meanwhile, the actual news content is roughly the same.

I quite like the idea of storm-driven development.

…websites built for a storm do not rely on Javascript. The benefit simply does not outweigh the cost. They rely on resilient HTML, because that’s all that is really necessary here.

Friday, September 28th, 2018

DasSur.ma – The 9am rush hour

Why JavaScript is a real performance bottleneck:

Rush hour. The worst time of day to travel. For many it’s not possible to travel at any other time of day because they need to get to work by 9am.

This is exactly what a lot of web code looks like today: everything runs on a single thread, the main thread, and the traffic is bad. In fact, it’s even more extreme than that: there’s one lane all from the city center to the outskirts, and quite literally everyone is on the road, even if they don’t need to be at the office by 9am.

Thoughts on Offline-first | Trys Mudford

Service Workers have such huge potential power, and I feel like we (developers on the web) have barely scratched the surface with what’s possible.

Needless to say, I couldn’t agree more!

Trys is thinking through some of the implicatons of service workers, like how we refresh stale content, and how we deal with slow networks—something that’s actually more of a challenge than dealing with no network connection at all.

There’s some good food for thought here.

I’m so excited to see how we can use Service Workers to improve the web.

Wednesday, September 26th, 2018

How to Build a Low-tech Website?

This is fascinating! A website that’s fast and nimble, not for performance reasons, but to reduce energy consumption. It’s using static files, system fonts and dithered images. And no third-party scripts.

Thanks to a low-tech web design, we managed to decrease the average page size of the blog by a factor of five compared to the old design – all while making the website visually more attractive (and mobile-friendly). Secondly, our new website runs 100% on solar power, not just in words, but in reality: it has its own energy storage and will go off-line during longer periods of cloudy weather.

Ping! That’s the sound of my brain going “service worker!”

I’ve sent them an email offering my help.

Thursday, September 20th, 2018

The costs and benefits of tracking scripts – business vs. user // Sebastian Greger

I am having a hard time seeing the business benefits weighing in more than the user cost (at least for those many organisations out there who rarely ever put that data to proper use). After all, keeping the costs low for the user should be in the core interest of the business as well.

A framework for web performance

Here at Clearleft, we’ve recently been doing some front-end consultancy. That prompted me to jot down thoughts on design principles and performance:

We continued with some more performance work this week. Having already covered some of the nitty-gritty performance tactics like font-loading, image optimisation, etc., we wanted to take a step back and formulate an ongoing strategy for performance.

When it comes to web performance, the eternal question is “What should we measure?” The answer to that question will determine where you then concentrate your efforts—whatever it is your measuring, that’s what you’ll be looking to improve.

I started by drawing a distinction between measurements of quantities and measurements of time. Quantities are quite easy to measure. You can measure these quantities using nothing more than browser dev tools:

  • overall file size (page weight + assets), and
  • number of requests.

I think it’s good to measure these quantities, and I think it’s good to have a performance budget for them. But I also think they’re table stakes. They don’t actually tell you much about the impact that performance is having on the user experience. For that, we need to enumerate moments in time:

  • time to first byte,
  • time to first render,
  • time to first meaningful paint, and
  • time to first meaningful interaction.

There’s one more moment in time, which is the time until DOM content is loaded. But I’m not sure that has a direct effect on how performance is perceived, so it feels like it belongs more in the category of quantities than time.

Next, we listed out all the factors that could affect each of the moments in time. For example, the time to first byte depends on the speed of the network that the user is on. It also depends on how speedily your server (or Content Delivery Network) can return a response. Meanwhile, time to first render is affected by the speed of the user’s network, but it’s also affected by how many blocking elements are on the critical path.

By listing all the factors out, we can draw a distinction between the factors that are outside of our control, and the factors that we can do something about. So while we might not be able to do anything about the speed of the user’s network, we might well be able to optimise the speed at which our server returns a response, or we might be able to defer some assets that are currently blocking the critical path.

Factors
1st byte
  • server speed
  • network speed
1st render
  • network speed
  • critical path assets
1st meaningful paint
  • network speed
  • font-loading strategy
  • image optimisation
1st meaningful interaction
  • network speed
  • device processing power
  • JavaScript size

So far, everything in our list of performance-affecting factors is related to the first visit. It’s worth drawing up a second list to document all the factors for subsequent visits. This will look the same as the list for first visits, but with the crucial difference that caching now becomes a factor.

First visit factors Repeat visit factors
1st byte
  • server speed
  • network speed
  • server speed
  • network speed
  • caching
1st render
  • network speed
  • critical path assets
  • network speed
  • critical path assets
  • caching
1st meaningful paint
  • network speed
  • font-loading strategy
  • image optimisation
  • network speed
  • font-loading strategy
  • image optimisation
  • caching
1st meaningful interaction
  • network speed
  • device processing power
  • JavaScript size
  • network speed
  • device processing power
  • JavaScript size
  • caching

Alright. Now it’s time to get some numbers for each of the four moments in time. I use Web Page Test for this. Choose a realistic setting, like 3G on an Android from the East coast of the USA. Under advanced settings, be sure to select “First View and Repeat View” so that you can put those numbers in two different columns.

Here are some numbers for adactio.com:

First visit time Repeat visit time
1st byte 1.476 seconds 1.215 seconds
1st render 2.633 seconds 1.930 seconds
1st meaningful paint 2.633 seconds 1.930 seconds
1st meaningful interaction 2.868 seconds 2.083 seconds

I’m getting the same numbers for first render as first meaningful paint. That tells me that there’s no point in trying to optimise my font-loading, for example …which makes total sense, because adactio.com isn’t using any web fonts. But on a different site, you might see a big gap between those numbers.

I am seeing a gap between time to first byte and time to first render. That tells me that I might be able to get some blocking requests off the critical path. Sure enough, I’m currently referencing an external stylesheet in the head of adactio.com—if I were to inline critical styles and defer the loading of that stylesheet, I should be able to narrow that gap.

A straightforward site like adactio.com isn’t going to have much to worry about when it comes to the time to first meaningful interaction, but on other sites, this can be a significant bottleneck. If you’re sending UI elements in the initial HTML, but then waiting for JavaScript to “hydrate” those elements into working, the user can end up in an uncanny valley of tapping on page elements that look fine, but aren’t ready yet.

My point is, you’re going to see very different distributions of numbers depending on the kind of site you’re testing. There’s no one-size-fits-all metric to focus on.

Now that you’ve got numbers for how your site is currently performing, you can create two new columns: one of those is a list of first-visit targets, the other is a list of repeat-visit targets for each moment in time. Try to keep them realistic.

For example, if I could reduce the time to first render on adactio.com by 0.5 seconds, my goals would look like this:

First visit goal Repeat visit goal
1st byte 1.476 seconds 1.215 seconds
1st render 2.133 seconds 1.430 seconds
1st meaningful paint 2.133 seconds 1.430 seconds
1st meaningful interaction 2.368 seconds 1.583 seconds

See how the 0.5 seconds saving cascades down into the other numbers?

Alright! Now I’ve got something to aim for. It might also be worth having an extra column to record which of the moments in time are high priority, which are medium priority, and which are low priority.

Priority
1st byte Medium
1st render High
1st meaningful paint Low
1st meaningful interaction Low

Your goals and priorities may be quite different.

I think this is a fairly useful framework for figuring out where to focus when it comes to web performance. If you’d like to give it a go, I’ve made a web performance chart for you to print out and fill in. Here’s a PDF version if that’s easier for printing. Or you can download the HTML version if you want to edit it.

I have to say, I’m really enjoying the front-end consultancy work we’ve been doing at Clearleft around performance and related technologies, like offline functionality. I’d like to do more of it. If you’d like some help in prioritising performance at your company, please get in touch. Let’s make the web faster together.

Tuesday, September 18th, 2018

Winston Hearn | What’s best for users

The incentives that Google technology created were very important in the evolution of this current stage of the web. I think we should be skeptical of AMP because once again a single company’s technology – the same single company – is creating the incentives for where we go next.

A thorough examination of the incentives that led to AMP, and the dangers of what could happen next:

I’m not sure I am yet willing to cede the web to a single monopolized company.

Friday, September 14th, 2018

Breaking the Deadlock Between User Experience and Developer Experience · An A List Apart Article

Yes! Yes! Yes!

Our efforts to measure and improve UX are packed with tragically ironic attempts to love our users: we try to find ways to improve our app experiences by bloating them with analytics, split testing, behavioral analysis, and Net Promoter Score popovers. We stack plugins on top of third-party libraries on top of frameworks in the name of making websites “better”—whether it’s something misguided, like adding a carousel to appease some executive’s burning desire to get everything “above the fold,” or something truly intended to help people, like a support chat overlay. Often the net result is a slower page load, a frustrating experience, and/or (usually “and”) a ton of extra code and assets transferred to the browser.

Even tools that are supposed to help measure performance in order to make improvements—like, say, Real User Monitoring—require you to add a script to your web pages …thereby increasing the file size and degrading performance! It’s ironic, in that Alanis Morissette sense of not understanding what irony is.

Stacking tools upon tools may solve our problems, but it’s creating a Jenga tower of problems for our users.

This is a great article about evaluating technology.

On using tracking scripts | justmarkup

Weighing up the pros and cons of adding tracking scripts to a website, from a business perspective and from a user perspective.

When looking at the costs versus the benefits it is hard to believe that almost every website is using tracking scripts.

The next time, you implement a tracking script it would be great if you could rethink it and ask yourself if it is really worth it.

Wednesday, September 12th, 2018

Private by Default

Feedbin has removed third-party iframes and JavaScript (oEmbed provides a nice alternative), as well as stripping out Google Analytics, and even web fonts that aren’t self-hosted. This is excellent!

Tuesday, September 11th, 2018

The “Developer Experience” Bait-and-Switch | Infrequently Noted

JavaScript is the web’s CO2. We need some of it, but too much puts the entire ecosystem at risk. Those who emit the most are furthest from suffering the consequences — until the ecosystem collapses. The web will not succeed in the markets and form-factors where computing is headed unless we get JS emissions under control.

Damn, that’s a fine opening! And the rest of this post by Alex is pretty darn great too. He’s absolutely right in calling out the fetishisation of developer experience at the expense of user needs:

The swap is executed by implying that by making things better for developers, users will eventually benefit equivalently. The unstated agreement is that developers share all of the same goals with the same intensity as end users and even managers. This is not true.

I have a feeling that this will be a very bitter pill for many developers to swallow:

If one views the web as a way to address a fixed market of existing, wealthy web users, then it’s reasonable to bias towards richness and lower production costs. If, on the other hand, our primary challenge is in growing the web along with the growth of computing overall, the ability to reasonably access content bumps up in priority. If you believe the web’s future to be at risk due to the unusability of most web experiences for most users, then discussion of developer comfort that isn’t tied to demonstrable gains for marginalized users is at best misguided.

Oh,captain, my captain!

Tools that cost the poorest users to pay wealthy developers are bunk.

The top four web performance challenges

Danielle and I have been doing some front-end consultancy for a local client recently.

We’ve both been enjoying it a lot—it’s exhausting but rewarding work. So if you’d like us to come in and spend a few days with your company’s dev team, please get in touch.

I’ve certainly enjoyed the opportunity to watch Danielle in action, leading a workshop on refactoring React components in a pattern library. She’s incredibly knowledgable in that area.

I’m clueless when it comes to React, but I really enjoy getting down to the nitty-gritty of browser features—HTML, CSS, and JavaScript APIs. Our skillsets complement one another nicely.

This recent work was what prompted my thoughts around the principles of robustness and least power. We spent a day evaluating a continuum of related front-end concerns: semantics, accessibility, performance, and SEO.

When it came to performance, a lot of the work was around figuring out the most suitable metric to prioritise:

  • time to first byte,
  • time to first render,
  • time to first meaningful paint, or
  • time to first meaningful interaction.

And that doesn’t even cover the more easily-measurable numbers like:

  • overall file size,
  • number of requests, or
  • pagespeed insights score.

One outcome was to realise that there’s a tendency (in performance, accessibility, or SEO) to focus on what’s easily measureable, not because it’s necessarily what matters, but precisely because it is easy to measure.

Then we got down to some nuts’n’bolts technology decisions. I took a step back and looked at the state of performance across the web. I thought it would be fun to rank the most troublesome technologies in order of tricksiness. I came up with a top four list.

Here we go, counting down from four to the number one spot…

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).

Fortunately there’s a straightforward question to ask in this situation: WWZD—What Would Zach Do?

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.

So, as with web fonts, it feels like the impact of images on performance can be handled, as long as you give them some time and attention.

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.

So stop sending so much JavaScript—a solution as simple as Monty Python’s instructions for playing the flute.

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.

It’s so disheartening when you’ve devoted your time and energy into your web font loading strategy, and optimising your images, and unbundling your JavaScript …only to have someone else’s JavaScript just shit all over your nice performance budget.

Here’s the really annoying thing: when I go to performance conferences, or participate in performance discussions, you know who’s nowhere to be found? The people making those third-party scripts.

The narrative around front-end performance is that it’s up to us developers to take responsibility for how our websites perform. But by far the biggest performance impact comes from third-party scripts.

There is a solution to this, but it’s not a technical one. We could refuse to add overweight (and in many cases, unethical) third-party scripts to the sites we build.

I have many, many issues with Google’s AMP project, but I completely acknowledge that it solves a political problem:

No external JavaScript is allowed in an AMP HTML document. This covers third-party libraries, advertising and tracking scripts. This is A-okay with me.

The reasons given for this ban are related to performance and I agree with them completely. Big bloated JavaScript libraries are one of the biggest performance killers on the web.

But how can we take that lesson from AMP and apply it to all our web pages? If we simply refuse to be the one to add those third-party scripts, we get fired, and somebody else comes in who is willing to poison web pages with third-party scripts. There’s nothing to stop companies doing that.

Unless…

Suppose we were to all make a pact that we would stand in solidarity with any of our fellow developers in that sort of situation. A sort of joining-together. A union, if you will.

There is power in a factory, power in the land, power in the hands of the worker, but it all amounts to nothing if together we don’t stand.

There is power in a union.