Optimizing Your Web Performance: Separating the Signals from the Noise

Carl, what is the focus of your work these days? 

I am the Director of Engineering for the front-end at Trainline. In essence, it means that I'm responsible for all externally facing teams, such as our iOS and Android applications, but also Web, landing pages, and also APIs serving customers.

What is the motivation for your talk?

The talk will be about optimizing Web performance, and I'll talk about the journey that we've been on over the last years. Optimizing web performance is actually much harder than it sounds. The complexity lies in the fact there isn’t a single metric to measure speed. The most common mistake is to focus on a specific metric as TTI or page load time, when in reality what you want to focus on is on the user experience.

What we found out on our journey is that whenever you focus on just the page load time, or the interactivity or maybe just the visual stability of your pages, it's always at the expense of another one. So the goal is really to measure all the things that make for a great page experience, keep the data and measure continuously, to learn what changes in your codebase will have an impact in production to your users, and then just refine and try to find the right balance.

It's always a fashionable topic, but even more right now because Google is actually changing the Google Search ranking algorithm to consider Core Web Vitals, making it more important than ever!

What would be the level and the persona of the attendees of your presentation?

I think anyone can come in. The idea is to start from what performance is, how do we measure it, and then just go step by step into the right methodology to improve it. I think it speaks to pretty much everyone. It's not linked to a specific technology. I mean, if you're React, ember.js, JQuery, vanilla JS, anyone can understand it. And we're really focusing on performance and how to optimize. It's not linked to any specific technology, so anyone interested in how to optimize web performance is welcome.

Would you be focusing more on what happens in the browser and how you can make the user experience faster? Will you be looking at delivery of the content, back-end stuff?

I don’t like those talks that give you those "one size fits all" solutions. It's more about giving you the methodology and the right monitoring so that I guarantee you that by applying these you’ll get there, you'll be able to spot those bottlenecks and you'll be able to know what your users experience from a speed perspective which is actually something that's very hard to do in a website. It's much easier in the back-end service because you can just monitor the time you spend in and out of the box. But in the browser, lots of things are happening, it's much more complex than monitoring the time that request took to complete: how do you measure how your user experiences your website? And how do you do it in a way that you can analyze so you can optimize, that’s what I’ll be focusing on in that talk.