the web performance conference11-12 November 2021, Amsterdam

Talks and speakers is a single track conference with fourteen world-class speakers, covering today’s most important web performance insights. They are selected by our program co-chairs Tammy Everts and Tim Kadlec.

Below is our line-up, including links to all slides and videos, of our second edition, which was held on 21st and 22nd of November, 2019. All sessions are geared toward delivering takeaway action items for teams creating fast web experiences across all devices.

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Henri Helvetica

Freelance Developer, @HenriHelvetica

Henri is a freelance developer who has turned his interests to a passionate mix of site performance engineering and pinches of user experience. When not reading the deluge of daily research docs and case studies, or indiscriminately auditing sites in devtools, Henri can be found contributing back to the community: Toronto Web Performance Group meetup + SPOTLIGHT: PERFORMANCE conference co-organizer, curating performance content for conferences or volunteering his time for lunch and learns at various bootcamps. Additionally, you can find him speaking at conferences, and touching base with the community—all with a radiant smile. Otherwise, he’s focusing on running the fastest 5k possible (surprise surprise).

A Decade of Disciplined Delivery

In 2019, we live in an age of immediacy. We make demands for speedier processes, or at the very least - less wait times. All industries and services have scrutinized operations in ways to make things as expeditious as possible.

When writing the influential tool FireBug, Firefox’s Joe Hewitt mentioned measuring load times as an objective. The same year, some equally influential writing was released: “High Performance Web Sites”, a book by SpeedCurve’s Steve Souders. Mr Souders had introduced 14 rules for front end engineers to live by, or how he openly opined: 14 rules to faster loading web sites.

Just over a decade later, the very websites we scrutinized for speed have matured, but so has the idea of speed itself. What was once a simple stopwatch measurement has turned to a metric in part proof and perception. But what of the 14 rules? “A Decade Of Disciplined Delivery” is a curious retrospective look at how the 14 rules apply today in 2019 in our quest to deliver and load resources as quickly as possible.

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Tammy Everts, MC

Chief Experience Officer, SpeedCurve, @tameverts

Tammy is chief experience officer at SpeedCurve, where she helps companies understand how visitors use their websites, and a cochair of O’Reilly Fluent. Tammy has spent the past two decades studying how people use the web. Since 2009, she’s focused on the intersection between web performance, user experience, and business metrics. Her book, Time Is Money: The Business Value of Web Performance from O’Reilly, is a distillation of much of this research. She also cocurates (with Tim Kadlec) WPO Stats, a collection of performance case studies.

The 7 Habits of Highly Effective Performance Teams

Over the past year, Tammy has talked with companies of all types – retail, media, travel, software, and more – and all sizes – from SMBs to huge enterprises. She was inspired to see how different organizations approach creating a robust performance culture.

The one thing they all have in common is agreeing that performance culture is the single greatest success variable. Having a strong culture of performance can help:

  • Prevent regression
  • Reduce gatekeeping
  • Increase investment from the business

Tammy will share tips and best practices gleaned from scores of conversations with people and companies who are leading the way down the path to performance.

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Patrick Hamann

Principal Software Engineer, Fastly, @patrickhamann

Patrick is a Principal Software Engineer at Fastly where—among other things—he is helping to build a faster web for all. Prior to Fastly, he helped architect some of the world’s largest media websites including The Guardian and the Financial Times. When not speaking or ranting about performance, he enjoys spending his spare time with his family discovering new places and food.

WebAssembly – To the browser and beyond!

WebAssembly (or Wasm) is a compilation target for the open web; often considered a hard-to-approach performance optimisation for your browser applications - but it promises to be so much more than that!

It’s beginning to reshape how, and where, our applications can run, giving us the freedom to choose whichever language is best suited for the job, and the most appropriate location to run it, be that the client, edge or server.

In this talk we’ll debunk some myths about WebAssembly and explore what it is and what it isn’t, its challenges, look at how we can use it practically in applications today, and what the future holds, both in the browser and beyond!

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Tatiana Mac

Independent Designer, @TatianaTMac

Tatiana is an independent American designer who works directly with organisations to build clear and coherent products and design systems. She believes the trifecta of performance, accessibility, and inclusion can work symbiotically to improve our social landscape digitally and physically. When ethically-minded, she thinks technologists can dismantle exclusionary systems in favor of community-focused, inclusive ones. Never totally pleased with design tools, she designs in browser to visual narratives into the web in a semantic and component-orientated way. Her current obsessions are optimising variable fonts, converting raster images into to SVGs, and recreating modernist paintings in CSS grid. When she can successfully escape vim, she finds new countries to explore (33 and counting).

How Privilege Defines Performance

In theory, web performance, accessibility, and inclusive design all have similar goals: Provide the best, most consistent experience to all people using the minimal amount of resources.

In practice, this often falls apart.

Product creators define what it means to be performant from where they stand, which is typically from places of privilege with unseen biases, struggling to find true empathy with their users.

Through this talk, we’ll examine how to build conscientiously, looking within to resist systematic problems in order to create more truly performant, accessible, and inclusive systems for our users.

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Stuart McMillan

Head of Multichannel, Tiso, @mcmillanstu

Stuart first started in ecommerce 17 years ago, selling tents and other outdoor equipment, before properly getting his geek on and moving in to a senior development role. Moving back in to a more general role, he worked for Schuh for seven years; his job description included responsibility for site performance, analytics and the quality of the conversion across all devices and being the champion for the multichannel, connected customer. He’s big advocate of web standards and appreciates a job well done. He brings a detailed technical appreciation to ecommerce, combined with a truly awful sense of humour.

He recently moved on from Schuh and is now Head of Multichannel for the outdoor retailer, Tiso, part of the JD Sports family. This is a real return to his retailing routes, again selling outdoor equipment. A broader role than in Schuh, his responsibilities are everything from Digital Marketing through User Experience to fulfillment.

7 Years of Never Shutting Up About Site Speed (Schuh case study)

Stuart will be presenting a case study of his seven years at Schuh, where they moved from having a “site speed problem” to “fastest in the UK”. What’s extraordinary about Schuh’s performance journey is how ordinary it is. They had (and in some cases continue to have) many of the same issues in common with most websites, and there is nothing revolutionary about the solutions. In many ways, this is a case study of hard work and persistence. But along the way there have been a few interesting problems to solve, from challenges with third parties, to challenges with third parties!

Stuart will cover a bit of theory and plenty of application, from measurement through to implementation, from processes to people.

[Video and slides taken down, sorry]

Emily Nakashima

Engineering Manager, Honeycomb, @eanakashima

Emily manages the engineering & design teams at In the past, she’s worked on javascript, web perf optimization and client-side monitoring & telemetry at other developer tools companies like Bugsnag & GitHub. In her free time, she organizes an unconference called AndConf, makes many checklists, and likes to talk about disaster preparedness.

Observability is for User Happiness

Within the observability community, there’s a saying, “nines don’t matter if users aren’t happy,” meaning that 99.999% server uptime is a pointless goal if our customers aren’t having a fast, smooth, productive experience. But how do we know if users are happy? As members of the web performance community, we’ve been thinking about the best ways to answer that question for years. Now the observability community is asking the same questions, but coming at them from the opposite side of the stack. What can we learn from each other? Emily will talk about how approaching web performance through the lens of observability has changed the way her team thinks about performance instrumentation and optimization. She’ll cover the nuts & bolts of how Honeycomb instrumented its customer-facing web app, and she’ll show how the Honeycomb team is using this data to find and fix some of its trickiest performance issues, optimize customer productivity, and drive the design of new features.

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Ilya Grigorik

Web Performance Engineer, Google, @igrigorik

Ilya is a web performance engineer at Google, co-chair of the W3C Web Performance Working group, and author of High Performance Browser Networking (O’Reilly) book.

Are we there yet? We’ve been at this make-performance-happen-now game for over a decade but the progress is slow: adoption of basic best practices (e.g. optimizing images, optimizing critical path, etc) is a struggle; inconsistent adoption of HTTP/2 priorities signals industry hurdles we didn’t account for; we’re back at the drawing board on key performance primitives (e.g. prefetch and prerender) that were supposed to save the day. Why, what are the reasons, and what can we do to improve our odds as we head into the new decade? Let’s talk.

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Harry Roberts

Consultant Performance Engineer, @csswizardry

With a client list including Google, Unilever, and the United Nations, Harry is an award-winning Consultant Front-end Architect who helps organisations and teams across the globe to plan, build, and maintain product-scale UIs.

A Google Developer Expert, and Performance Ambassador for SHIFT Commerce, he writes on the subjects of CSS architecture, performance, and scalability at, develops and maintains inuitcss, authored CSS Guidelines, and Tweets at @csswizardry.

Harry will also host a workshop on Front-End Performance.

From Milliseconds to Millions: A Look at the Numbers Driving Web Performance

We all know performance is big business, but how big? Let’s take a look at some of the numbers powering the web performance industry from both sides of the table. What do performance improvements mean for my clients, and how do we translate that into a working relationship?

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Patrick Meenan

Web Performance Engineer, Facebook, @patmeenan

Patrick has been working on web performance in one form or another for the last 20 years and is currently working on web performance at Facebook. Prior to that he worked at Cloudflare and Google to make Chrome and the web faster. Patrick created the popular open source WebPageTest web performance measurement tool and runs the free instance of it at

HTTP/2 priorities

Patrick will dive into the details of HTTP/2 prioritization, how it interacts with the browser and your content and how to get the most out of it. He will also explore the various ways it can go wrong in a production environment and how to validate your deployment to make sure it is working optimally. He will also explore recent developments with HTTP/3 and the changes that will bring to the table.

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Divya Sasidharan

Developer Experience Engineer, Netlify, @shortdiv

Divya is a web developer who is passionate about open source and the web. She is currently a developer experience engineer at Netlify, and believes that there is a better workflow for building and deploying sites that doesn’t require a server—ask her about the JAMstack. You will most likely find her in the sunniest spot in the room with a cup of tea in hand.

Predictive Prefetching

Some of the most cutting edge and effective web performance optimizations, like prefetch and preconnect, involve being proactive. We make predictions to determine where a user is likely to go next and load resources ahead of time so page load is as fast as possible. This is where machine learning comes in handy. By training a machine learning model (maybe a markov chain?) with current analytics data, we can take the guess work our of our predictions and more accurately load resources ahead of time. In this talk, we will examine techniques currently being developed, like GuessJS to make predictive prefetching a reality.

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Tim Kadlec, MC

Performance Consultant, @tkadlec

Tim is a performance consultant and trainer focused on building a web everyone can use. He is the author of High Performance Images (O’Reilly, 2016) and Implementing Responsive Design: Building sites for an anywhere, everywhere web (New Riders, 2012), and was a contributing author for Smashing Book #4: New Perspectives on Web Design (Smashing Magazine, 2013), and the Web Performance Daybook Volume 2 (O’Reilly, 2012). He writes about all things web at You can find him sharing his thoughts in a briefer format on Twitter at @tkadlec.

When JavaScript Bytes

JavaScript is, byte-for-byte, the most expensive resource on the web and we’re using more of it than ever in our sites. You can optimize the delivery, the parsing and the execution until you’re blue in the face but you’ll never make it as performant as simply not using it in the first place.

But what do you do if you’re already staring down a pile of scripts?

In this talk, we’ll discuss practical ways to reduce the amount of JavaScript we’re sending down to the people using our sites. We’ll look at techniques for shaving excess bytes off our bundles and, just as critically, tools and approaches we can use to make sure those bytes stay off.

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Simon Hearne

Web Performance Solutions Engineer, Akamai, @simonhearne

Simon is passionate about web performance. He has been working in the industry since 2012 in roles as diverse as professional services, software engineering and solutions engineering. His current role is to help his clients achieve excellent user experiences through monitoring, testing and managing web performance.

Deep dive into third-party performance

In this talk we will get deep into HTTP Archive, browser developer tools and Real User Monitoring (RUM) data. We’ll discover which third-party tags have the greatest impact on user experience, how ad blockers impact site speed and what to look out for when evaluating a new third-party service. Most importantly, we will discuss techniques to manage third-party performance & security without creating friction with marketing and analytics teams!

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Annie Sullivan

Software Engineer, Google, @anniesullie

Annie is a software engineer with Google. She is passionate about building a better performing web for users across the globe. Her tenure as a Googler spans 14 years, with experience on the toolbar, docs, web search, and chrome teams. Annie most recently comes from a tour-of-duty with the United States Digital Service, a tech startup at the White House, where she contributed to projects at the Department of Energy. She lives in Michigan with her husband Doug and two sons. See her laser engraved art at

Lessons learned from performance monitoring in Chrome

Annie has done a lot of work on performance metrics and monitoring for Chrome over the past several years. She’ll talk about what she’s learned in that time, and how it can be applied to web site performance monitoring. She will cover performance metric and benchmark design, dealing with benchmark noise in the lab, and understanding the subtleties of RUM data.

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Vitaly Friedman

Creative lead, Smashing Magazine, @smashingmag

Vitaly loves beautiful content and does not give up easily. From Minsk in Belarus, he studied computer science and mathematics in Germany, discovered the passage a passion for typography, writing and design. After working as a freelance designer and developer for 6 years, he co-founded Smashing Magazine, a leading online magazine dedicated to design and web development. Vitaly is the author, co-author and editor of all Smashing books. He currently works as editor-in-chief of Smashing Magazine in the lovely city of Vilnius, Lithuania.

The Future of Performance

We’ve come quite far in web performance over the last decade, haven’t we? The connections are better than ever, the browsers smarter than ever, HTTP/2 is omnipresent and 5G is right here at the horizon! In fact, we’ve invented and mastered fancy code-splitting and tree-shaking techniques, reinvented bundling of assets in the world of HTTP/2 and learned how to minimize the payload to deploy fast and render soon. Are we done yet?

Not really. In this session, we’ll look into areas that still need some work to be done. What about next-generation image formats and video encoders? What about wide-established progressive rehydration and lazy-loaded frameworks? What about progressive deployment with JAM Stack and universal Brotli compression by default? We’ll also touch on priority hints, cutting-edge strategies for service workers, subsetting typographic spaces with variable fonts, performance optimization with Network Information API and Device Memory API, runtime optimizations with WebAssembly and analytics-based, predictive performance optimization. Also, we’ll explore the privacy/authentication aspects of performance and how new development will change the way we build and deploy on the web. The future isn’t here yet, let’s examine what it might bring to all of us!

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