Karlijn Löwik: Web performance in 2025: putting real UX first

You got a 100% Lighthouse score? Hold the celebration! Core Web Vitals may disagree, and even they have survivor bias, ignoring your slowest users and everyone who bounced before loading. Real user data tells the real story. Join Karlijn and Erwin as we combine Google's latest DevTools insights with real user monitoring to show why standard metrics mislead, how to spot hidden speed blockers, and focus on what users actually experience. We'll cut through the noise with practical tools and real-world data to fix what truly matters. Want to see past those vanity scores? We'll guide you there with some memes along the way.

You might know Karlijn Löwik for one of these two things: terrible puns about SUX (Sitespeed User Experience) or her memes that make learning about Core Web Vitals actually fun. As CEO & Co-founder of RUMvision, a real user monitoring company, she works to make web performance accessible to everyone. The fact that she co-founded the company with her web performance specialist husband Erwin Hofman just makes their story even better.

Based in Groningen with their 4-year-old, Karlijn's talk titles are hard to forget - think "SUX on the Beach" for summer conferences and "SUX and the City" in New York. She serves as co-chair for the RUM W3C Group and board member of Mage-OS NL, building communities that care about performance and beyond.

She speaks at events solo or sometimes with Erwin (they haven't managed to kill each other on stage yet). Their work takes them around the world, and they've gotten good at turning business trips into family adventures. When not creating memes or working, Karlijn loves to dance, cook, make cocktails (with rum, obviously), and advocate for women in tech.

Karlijn's mission is simple: help everyone understand why site speed matters, preferably while laughing. Because good SUX really does sell.