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This blog post has a simple conclusion: Load script asynchronously! Simple, and yet the reality is that most scripts are still loaded synchronously. Understanding the importance of loading scripts asynchronously might help increase adoption of this critical performance improvement, so we're going to walk through the evolution of async script loading starting way back in 2007. Here's what loading 14 scripts looked like in Internet Explorer 7:
The Internet really is a complicated series of tubes. As a result, any time-based metrics we capture can have variations as those tubes wobble a bit as we shove data down them. To help reduce that variation, when we do synthetic tests, we always load a page at least three times and take the median result. But even then you'll find that, over time, your charts will still show plenty of variation.
All that variation can make it difficult to see if your metrics are getting better or worse over time. We recently released a couple of new features in your Synthetic and LUX charts that make it easier for you to visualize trends and compare discrete time periods within your historical data.
To make it easier for you to see which direction your metrics are heading, we've added an option to all your charts to show a trend line which helps you visualize how a particular metric is changing over the timespan of the chart. You can hover over the legend to highlight a trend line or hover over any point on the trend to see the estimated value at that point.
The number of performance metrics is large and increases every year. It's important to understand what the different metrics represent and pick metrics that are important for your site. Our Evaluating rendering metrics post was a popular (and fun) way to compare and choose rendering metrics. Recently I created this timeline of performance metric medians from the HTTP Archive for the world's top ~1.3 million sites:
This week we've made some pretty exciting new changes to your Favorites dashboards. Aside from a brand-new chart editor interface, you'll also notice that we've introduced two new chart types: histograms and correlations.
In this post, I'm going to talk through some of the features in our new chart editor. I'll also explain in detail explain why I think histograms are such an important tool in your performance toolkit, and how you can get some fascinating insights by correlating other metrics on top of a histogram.
Here at SpeedCurve, we are continually gathering detailed performance data from tens of thousands of web pages. This gives us a relatively unique opportunity to analyse and aggregate performance metrics to gain some interesting insights. In this post, I'm going to analyse some browser-based paint timing metrics: First Paint & First Contentful Paint (defined in the Paint Timing spec and implemented in Chromium). I'm also going to analyse First Meaningful Paint (defined in a draft spec and implemented as a Chromium trace metric).
The aim of almost any performance optimisation on the web is to improve the user experience. The folk at Google have been pushing this sentiment with a focus on user-centric performance metrics, which aim to answer four questions about users’ experiences:
First Paint (FP) measures the point at which pixels are first rendered to the screen after navigating to a new page. First Contentful Paint (FCP) is slightly more specific, in that it measures the point at which text or graphics are first rendered to the screen. Both of these metrics are available in Chromium browsers (Chrome, Opera, Samsung Internet, etc) via the Performance API:
The paint timing metrics are important because they aim to answer the first question: is it happening? My analysis will look at performance data from some popular websites in an attempt to figure out whether the paint timing metrics really do answer that question.
One of the longest-standing items on my performance monitoring tool wishlist is an automatically-generated performance improvement checklist, with the improvements ordered by the impact that they will have on the website. In a previous life, I spent countless hours writing performance reports and conducting A/B performance tests to figure out which change would have the biggest impact on a website's performance.
So I'm understandably very excited that today we're announcing the new Improve dashboard – a prioritised performance improvement checklist that aggregates Lighthouse and Google PageSpeed results across all the URLs in your site to identify the most impactful performance changes you can make.
In the year since Google rolled out Lighthouse, it's safe to say that "Will you be adding Lighthouse scoring?" is one the most common questions we've fielded here at SpeedCurve HQ. And since Google cranked up the pressure on sites to deliver better mobile performance (or suffer the SEO consequences) earlier this month, we've been getting that question even more often.
We take a rigorous approach to adding new metrics. We think the best solution is always to give you the right data, not just more data. So we're very happy to announce that after much analysis and consideration, we've added Lighthouse scores to SpeedCurve. Here's why – as well as how you can see your scores if you're already a SpeedCurve user.
When looking to improve the performance and user experience of our sites we often start by looking at the network:
What's the time to first byte?
How many requests are we making and how long are they taking?
What's blocking the browser from rendering my precious pixels?
While these are entirely valid questions, over the last few years we've seen a growing number of web performance issues that are caused, not by the network, but by the browser's main thread getting clogged up by excessive CPU usage.
We're excited to announce the availability of the First Input Delay metric as part of LUX, SpeedCurve's RUM product.
This may sound counter-intuitive, but we don't want you to spend countless hours using SpeedCurve. In fact, our goal is to make your web performance data so accessible, understandable, and actionable that you can get everything you need from us in just a few minutes.
That's why we're so excited to announce the brand-new Status dashboard – a visualization that lets you see at a glance all your web performance budgets, as well as which budgets have been violated.
Keep reading to find out how to start using your Status dashboard to diagnose and fix your performance pains. But first, let's talk about why we built this feature.
Part of building a strong performance culture in an organisation is lowering the barrier to getting people excited about performance. One of the most effective ways I've found to do this is to send around a performance report every week that can, at a glance, answer an important question: did performance get better or worse?
That was the motivation behind our new Weekly Report feature. Now you can configure any of your Favorites dashboards to be summarized in a weekly email, like this one:
It's exciting working at SpeedCurve and pushing the envelope on performance monitoring to better measure the user's experience. We believe when it comes to web performance it's important to measure what the user sees and experiences when they interact with your site. A big part of our focus on metrics has been around rendering including comparing TTI to FMP, Hero Rendering, and critical blocking resources.
The main bottleneck when it comes to rendering is the browser main thread getting blocked. This is why we launched CPU charts for synthetic testing over a year ago. Back then it wasn't possible to gather CPU information using real user monitoring (RUM), but the Long Tasks API changes that. Starting today, you can track how CPU impacts your users with SpeedCurve's RUM product, LUX.
We're excited to announce that we've launched Last Painted Hero as an official metric. Last Painted Hero is a synthetic metric that shows you when the last piece of critical content is painted. Keep reading to learn how Last Painted Hero works, why (and how) we created it, and how it can help you understand how your users perceive the speed of your pages.
When choosing the right performance metric, my soapbox for the last few years has been "not every pixel has the same value". In other words, rather than chase dozens of different performance metrics, focus on the metrics that measure what's critical in your page.
Here at SpeedCurve, we think it's good to focus on rendering metrics, because they're a closer approximation to what the user experiences. There are some good rendering metrics out there, like start render and Speed Index, but the downside to these metrics is that they give every pixel the same value. For example, if the background renders and some ads render, that could improve your start render time and Speed Index score, but it might not have a big impact on the user's experience. Instead, it's better to measure the parts of the page that matter the most to users. We call those parts of the page the "hero elements".
We're excited to announce that SpeedCurve is partnering with Tim Kadlec to provide consulting services to our customers!
Tim is a recognized expert when it comes to web performance. He has spoken at numerous conferences including Velocity, Fluent, QCon, SmashingConf, Beyond Tellerand, and WebStock. He wrote High Performance Images and Implementing Responsive Design, as well as contributing to other books. Mark, Tammy and I have each collaborated with Tim on side projects. We're full of gleeful anticipation as we look forward to this opportunity to work together again.
In the first sentence I mentioned that this is a partnership. Here's what that means: Tim will continue to do consulting outside of SpeedCurve, and if you're not a SpeedCurve customer we encourage you to contact him directly. Tim will also be running SpeedCurve's consulting services. This partnership brings special advantages to SpeedCurve customers:
SpeedCurve comes with a great set of dashboards for synthetic and RUM. But we know that one size does not fit all when it comes to data charts, which is why we've invested so much work into the Favorites dashboards. For customers who use LUX, it provides a place to create custom charts that combine metrics from synthetic and RUM.
We just added some new RUM metrics from LUX in Favorites to allow for even more customized monitoring:
We’re kicking off 2018 with a bang and a donut. We’ve been busy preparing all-new faster test agents and they’re now available for you to switch to – at no extra cost!
Go to your Settings to switch to faster test agents.
All our agents now run on much faster AWS C4.Large instances, which better approximate current desktop browsers. We’ve also switched to the latest WebPageTest agent running on Linux.
How much faster? 20-30%
When you switch to the new agents, some of your metrics will get 20-30% faster, so pick a time to switch that suits your team. In between projects or the start of the month are good times to set a new baseline.
One of the best parts of my job is getting to talk to so many people from so many different companies about web performance. Every company is different, and I learn a ton from talking to each one. But one question that almost every person asks me – regardless of what industry they're in or the size of their organization – is this:
How can I create a stronger culture of web performance at my company?
Creating a performance culture means creating a feedback loop in your company or team that looks like this:
In other words: Get people to care, show them what they can do to help, and then give them positive reinforcement when you get results. It's basic human psychology, and it might seem obvious when you see it in a super-simple graphic. But it's surprisingly easy to miss these steps and instead skip ahead to the part where you invest in awesome performance tools, and then wonder why all your performance efforts feel like such a painful uphill slog.
In this post, I'm going to share some proven tips and best practices to help you create a healthy, happy, celebratory performance culture.
At SpeedCurve, we're fond of the phrase "a joyous user experience". Creating this joy requires delivering what users want as quickly as possible. It's important that the critical content is downloaded and rendered before users get frustrated.
Network metrics have been around for decades, but rendering metrics are newer. Speed Index. Start Render. Time to First Interactive. First Meaningful Paint. These are a few of the rendering metrics that currently exist. What do they mean? How do they compare? Which are best for you? Let's take a look.
Rolling out new features is always a blast, and it's extra rewarding when the new feature is a response to a customer request. We've had many conversations with SpeedCurve users who've told us that multiple Favorite dashboards would be a huge benefit for their teams.
Today, we're very excited to announce that multiple Favorites dashboards are now available. Here's why you need them and how to create them.
One of the best – and worst – things about real user monitoring is that it gives you unparalleled access to massive amounts of user data. The problem is when all this data leads to data indigestion. How do you know where to begin? And how do you know what to leave out in order to present a clear case for performance?
At SpeedCurve, we care about more than just showing you all your data. We want to show you the most important data. And we want to make it easy for you to share that data with people throughout your organization. That’s why we’re excited about the newest addition to our family of visualizations: engagement charts.
Being able to track which changes have an impact – either positive or negative – on your site’s performance is an important part of performance monitoring that can provide valuable feedback to your team. We wanted to make it easier to see at a glance all the changes to your site, without the cognitive overhead of interpreting charts. That’s why we created the new Changes dashboard, which gives you a newsfeed-style overview of recent activity in your SpeedCurve account.
Your Changes dashboard shows your performance budget alerts, deploys, site notes, and SpeedCurve product updates: