Saturday, February 23rd, 2019
Wednesday, February 20th, 2019
If you really, really have to add Google Analytics to a sites, here’s a way to do it in a more performant way, without the odious Google Tag Manager.
Sunday, February 3rd, 2019
A spot-on description of how targetted advertising works …or rather, how it doesn’t.
They are still trying to sell me car insurance for my subway ride.
Friday, February 1st, 2019
Following on from that proposal for a browser feature that I linked to yesterday, Tim thinks through all the permutations and possibilities of user agents allowing users to throttle resources:
If a limit does get enforced (it’s important to remember this is still a big if right now), as long as it’s handled with care I can see it being an excellent thing for the web that prioritizes users, while still giving developers the ability to take control of the situation themselves.
Wednesday, January 9th, 2019
When you stop to consider all the implications of poor performance, it’s hard not to come to the conclusion that poor performance is an ethical issue.
Wednesday, December 19th, 2018
Friday, December 14th, 2018
GitHub - GoogleChromeLabs/quicklink: ⚡️Faster subsequent page-loads by prefetching in-viewport links during idle time
This looks like a very handle little performance-enhancing script: it attempts to prefetch some links, but in a responsible way. It won’t do any prefetching on slow connections or where data saving is enabled, and it only prefetches when the browser is idle.
Wednesday, November 21st, 2018
The tools that characterize a person’s time and place in technological history are the ones that a person actually uses, the technologies relied upon so heavily that they can feel like an extension of oneself. This is part of how technology can define a culture, and why sometimes you forget the thing you’re using is technology at all. Until, eventually, inevitably, the technology is all but forgotten.
Tuesday, November 13th, 2018
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.
Monday, November 12th, 2018
Saturday, November 10th, 2018
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
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
Harry divides his web performance work into three categories:
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
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
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 “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.
Friday, September 28th, 2018
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.
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
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
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.
|1st meaningful paint||
|1st meaningful interaction||
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 meaningful paint||
|1st meaningful interaction||
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.
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.
|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.
Friday, September 14th, 2018
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.