You open your website at the office, on good Wi-Fi and a new phone, and it loads instantly. Your customer opens it on the beach, with two bars of signal and a three-year-old phone. They stare at a white screen for four seconds, tap "back" and open the next result on Google.
You will never meet that customer. They don't leave a message or complain. They just don't come. That is why speed is one of the problems business owners almost never suspect.
What "slow" means to Google
Google measures speed with three numbers, the Core Web Vitals, and it measures them on real visitors, not in a lab. The limits for a "good" page are (web.dev):
- Largest Contentful Paint (LCP): up to 2.5 seconds. This is the moment the main photo or headline at the top of the page appears.
- Interaction to Next Paint (INP): up to 200 milliseconds. You tap a button or a menu and it should react straight away.
- Cumulative Layout Shift (CLS): up to 0.1. It measures how much the content jumps around while loading, like when you go to tap "Call" and a photo drops in at the last moment so you tap something else.
A page passes when at least three out of four of its visitors get a good result on all three.
Google says plainly that these numbers are used by its ranking systems, and also that relevant content matters more. A fast page will not reach the top just because it is fast. But when two guesthouses or two garages in the same area have similar pages, speed is what separates them.
How many customers it costs you
The best-known measurement is the "Milliseconds Make Millions" study that Deloitte ran for Google. It looked at 37 leading brand sites in Europe and America, with more than 30 million sessions, at the end of 2019. When a mobile site got faster by just 0.1 seconds, conversions rose by 10.1% on travel sites and by 8.4% on retail sites (web.dev). A tenth of a second.
In 2021 Vodafone ran a cleaner experiment: two versions of the same landing page, half the visitors to each, the only difference being that one was optimised for speed. When the main content appeared 31% sooner, sales went up 8% (web.dev).
These are large companies with millions of visitors, and the percentages don't carry over one to one to a guesthouse with ten rooms. The mechanism is the same, though: every second of waiting is a chance for the visitor to leave. And a small guesthouse or a taverna has fewer visitors to lose.
It isn't the network
The first thought is usually "it's the signal". Most of the time it isn't. At the end of 2025 the median mobile download speed in Greece was about 120 Mbps, up 60% in a year (DataReportal).
What keeps growing is the pages themselves. The typical mobile home page weighed about 2.6 MB in 2025, 8.4% more than in 2024. Of that, almost 0.9 MB was images and more than 0.6 MB was JavaScript (HTTP Archive). Code is the expensive part: it doesn't just have to download, it has to run, and a mid-range phone runs it far more slowly than your laptop.
The result: in 2025 only 48% of websites passed all three checks on mobile (HTTP Archive). More than half don't.
The usual suspects
On small business websites I keep seeing the same things:
- Photos straight from the camera or phone. A photo of several megabytes, uploaded as it is, to fill a screen a few centimetres wide. Resized properly and saved in a modern format, the same photo takes a small fraction of the space with no visible difference.
- Slideshows at the top of the page. Ten large photos that all load at once, while the visitor only ever sees the first.
- Plugins collected over the years. On off-the-shelf platforms every new feature is a plugin, and every plugin adds its own code to every page, even where it isn't used.
- Third-party services. A chat window, an embedded Instagram feed, a map, a video, several tracking tools. Each one loads from someone else's server and often weighs more than all the rest of the content.
- Too many fonts. Three font families with six weights each, for text that uses two.
- Cheap hosting far from your visitors. If the server is slow to answer, everything else waits.
How to check it yourself in five minutes
- Open PageSpeed Insights, enter your page's address and press "Analyze".
- Stay on the Mobile tab. The desktop tab almost always looks better.
- Look at the top section first, the Core Web Vitals assessment. That is data from real visitors, and it is what Google takes into account. The 0 to 100 score further down is a lab simulation: useful for seeing what is wrong, not the final verdict.
- If your site has few visitors, there may be no real-user data at all. Then you have the simulation, and the next test.
- Turn off Wi-Fi on your phone and open the page on mobile data, the way a customer would. If you are waiting, so are they.
If you use Google Search Console, its Core Web Vitals report shows which groups of pages have a problem, so you don't have to check them one by one.
What is easy to fix and what isn't
Photos are almost always easy to fix, and that alone usually makes the biggest difference. The same goes for third-party services: if the chat window hasn't brought a single message in the last year, it can go.
The harder part is the foundation of the site: a heavy theme, dozens of plugins that depend on each other, page builders that produce far more code than the page needs. At some point, fixing those costs more than a new, lightweight site.
The takeaway
Check your site today, on your own phone, on mobile data. If the main content takes more than two and a half seconds to appear, start with the photos and the third-party services. They are the two cheapest fixes and usually the most effective.
Speed and Core Web Vitals are part of my work on every site I build. If you'd like me to look at yours, write to me at [email protected].