A web designer on my feed recently shared a redesign they were very proud of. A website they had built for a client. It looked clean, modern — exactly what you'd expect a good designer to deliver.

So I ran it through Google PageSpeed Insights. It loaded in over 10 seconds on mobile. The Lighthouse performance score? 12 out of 100.

This is a story I see played out again and again, and it breaks my heart every time. Because the client has no idea. They see a beautiful new site and they're thrilled. They don't realise that Google is watching — and punishing them for it.

The sins that kill organic rankings

Let me walk you through what this particular site was doing wrong. These aren't edge cases — they're the most common mistakes made during redesigns.

1. Site speed

Page speed is a confirmed Google ranking factor, and Core Web Vitals are now part of the algorithm. A 10-second load time on mobile is catastrophic. Users will bounce, Google will notice, and your rankings will drop. No exceptions.

2. Intrusive interstitials

Pop-ups that cover the main content on mobile are penalised directly by Google. This includes newsletter sign-up overlays, cookie consent banners that take up the full screen, and app download prompts. Google has been vocal about this since 2017. Sites still do it.

3. Too many ads above the fold

If the first thing a user sees when they land on your page is advertising, Google considers that a poor user experience. Their Page Layout algorithm targets sites where content is pushed below the fold by ads. This is especially brutal on mobile.

4. Poor mobile UX

Tap targets too small. Text too small to read. Horizontal scrolling. These all fail the mobile usability report in Google Search Console — and they all signal a low-quality page to Google's crawlers.

What to do before any redesign

Before you sign off on a new design, run the current site through PageSpeed Insights and Lighthouse. Note the scores. Then run every major template of the new design through the same tools before it goes live. If the scores have dropped, do not launch.

A beautiful site that nobody sees is worth nothing. A fast, functional site that ranks well is worth everything.

If you're planning a redesign and you want to make sure you don't throw away your Google traffic in the process, get in touch. It's what I do.