Sia Karamalegos is a freelance web developer and web performance engineer helping ecommerce brands turn faster load times into real revenue. As a Google Developer Expert in Web Technologies and a former engineer on Shopify’s performance team, Sia brings a unique blend of hands-on experience and deep technical insight to the challenge of building faster, more performant online stores.

With a passion for developer education and community building, Sia organizes the Eleventy Meetup, Durham Social Hack Night, and a new global web performance meetup, connecting engineers around the world to share real-world tactics and tools. She’s also a frequent international speaker and writer, known for making complex topics like Core Web Vitals and JavaScript performance approachable and actionable.

In 2024, Sia launched ThemeVitals, a tool that benchmarks Shopify themes using real user data—not lab simulations to uncover which themes actually perform well across the devices your customers use. It’s a mission rooted in impact: helping merchants and theme developers make smarter, faster decisions that drive conversion and long-term growth.

Through her work, Sia is redefining how ecommerce teams think about performance, showing that real user data, smart defaults, and community-driven tooling can transform the way we build the web.

In This Conversation We Discuss:

• [00:40] Intro
• [01:00] Focusing on real-world site speed fixes
• [02:39] Improving performance metrics for merchants
• [04:22] Translating Google metrics for merchants
• [04:56] Understanding how Core Web Vitals work
• [07:34] Balancing traffic vs technical optimization
• [10:36] Shifting focus from speed to sales
• [13:16] Balancing performance with product experience
• [15:26] Highlighting global device performance gaps
• [16:54] Uploading giant images the wrong way
• [21:04] Auditing your tech stack regularly
• [21:53] Comparing Shopify themes with real data
• [24:11] Balancing features vs speed in theme choice
• [26:00] Avoiding minimalist themes that lack function
• [28:08] Encouraging feedback for future improvements

Resources:

• Subscribe to Honest Ecommerce on Youtube
• Explore real-world Core Web Vitals performance data for popular Shopify themes themevitals.com/
• Web Developer & Performance Engineer sia.codes/
• Follow Sia Karamalegos linkedin.com/in/karamalegos

If you’re enjoying the show, we’d love it if you left Honest Ecommerce a review on Apple Podcasts. It makes a huge impact on the success of the podcast, and we love reading every one of your reviews!