Front-end Performance Master Class


Performance matters. Research shows performance has a huge impact on conversion and user retention ( You as a front-end developer can make a big difference!

In this master class you will learn what makes websites slow and what you can do to make them fast. Step-by-step we will boost front-end performance for our real world example site. We will start with basic optimisations, learn how to automate them and work towards more advanced performance optimisations. Along the way you will learn all about how browsers render web pages.

At the end of the day you will leave with a lot of hands-on experience, which will empower you in your daily work.

We know a lot about performance. We recently rebuilt our own website and wrote this blog post ( about it, which was received well by the community.

Note: We will focus on server-side rendered websites. But you can also apply most optimisations to client-side web apps.

(Front-end) web developers.

An understanding of HTML, CSS and Javascript.

1 day course.

What will you learn

• Understand browser rendering
• Analyse front-end web performance
• Find performance bottlenecks
• Quick win performance optimisations
• Advanced performance optimisations


• Introduction: performance matters, perceived performance
• Critical rendering path
• Measuring performance: with Pagespeed Insights, WebPagetest and Chrome dev tools
• Basic performance optimisations: caching, gzipping, minification
• Image delivery: WebP, , [srcset], data URI’s
• Web fonts: font subsetting, FOIT vs FOUT, async font loading
• Lazy load JS: [async], [defer], loadJS
• Lazy load CSS: with critical CSSMoving towards
• HTTP/2


Declan Rek - Declan is De Voorhoede’s very own web performance specialist. He guided companies like eBay and Funda on ensuring they’re faster than their competition. Declan occasionally gives talks on performance and wrote a long article on how to boost performance on CSS Tricks (

Jasper Moelker - Jasper is a front-end architect and partner at De Voorhoede. Great user experiences for everyone are his drive to try new techniques and tools everyday to get the best (perceived) performance. He regularly presents at meetups and the occasional conference. Find him on Twitter ( and Github (


Ticket: €599 incl. 21% VAT (€495.04 excl. VAT)

Ticket with 25% freelance discount: €448,99 incl. 21% VAT (€371,07 excl. VAT)

Ticket & RSVP

You can buy your ticket here ( and RSVP in this meet-up event.

Maximum number of participants: 12

Do you still have questions about the workshop? Don't hesitate to ask!

Call us or send us an e-mail. (