Why is my website slow on mobile data, and how do I fix it?

Most people who visit your website will do it on a phone, and many of them on mobile data rather than Wi-Fi. If your site takes too long to show anything, plenty of them won't wait. They'll press back and choose the next result.

Speed also affects how you appear in Google. Google mainly uses the mobile version of your site when deciding where to rank it, and it looks at real loading experience as one of its signals.

The good news is that most slow websites are slow for the same handful of reasons.

First, test your site

You don't need technical skills to check your speed:

1. Go to PageSpeed Insights (pagespeed.web.dev), Google's free testing tool.
2. Enter your website address and run the test.
3. Look at the Mobile results first.

You'll see a score and a list of problems. Don't worry about getting a perfect 100. Focus on what the report lists under "Diagnose performance issues" and on the three Core Web Vitals:

• Largest Contentful Paint (LCP): how long until the main content appears.
• Interaction to Next Paint (INP): how quickly the page reacts when someone taps or types.
• Cumulative Layout Shift (CLS): whether things jump around while the page loads.

It's also worth simply opening your site on your own phone, on mobile data, away from the office Wi-Fi. Slow pages are obvious when you experience them yourself.

The usual reasons a website is slow

1. Huge images

This is the most common cause by far. A photo straight from a phone or camera can be several megabytes, and if it's uploaded as-is, every visitor downloads all of it, even to display it at the size of a postage stamp.

The fix: resize images to the size they're actually shown at, and use modern formats like WebP or AVIF, which are much smaller than JPEG at the same quality. Images further down the page should load only when the visitor scrolls near them ("lazy loading").

2. Too many plugins, scripts and widgets

Every chat widget, slider, tracking pixel, popup and social feed adds code the phone has to download and run. Website builders and WordPress sites with dozens of plugins are especially prone to this.

The fix: remove anything you don't actively use. For everything else, ask whether it's worth slowing down every single visit.

3. Slow or overcrowded hosting

Very cheap hosting often means your site shares a server with hundreds of others. When the server is busy, your page waits before it even starts loading.

The fix: choose hosting that matches your site, and use a CDN (content delivery network), which serves your site's files from locations closer to your visitors.

4. Autoplay videos and heavy sliders

A full-screen video or a five-image slider at the top of the page looks impressive on office Wi-Fi and painful on a phone. They also push your actual message further down.

The fix: lead with one strong, optimised image and a clear headline. If you need video, let people choose to play it.

5. Too many fonts

Each font and font weight is another file to download. Some sites load five or six without anyone noticing.

The fix: stick to one or two font families and only the weights you use.

6. No caching

Without caching, the server builds each page from scratch for every visitor, and returning visitors download the same files again.

The fix: make sure pages and files are cached properly. Many sites can even be served as pre-built pages, which load very quickly.

Should you fix it or rebuild?

Often, fixing images and removing unnecessary plugins makes a big difference in an afternoon. Try that first.

If your site is still slow afterwards, the problem may be how it was built: a heavy theme, a page builder that adds a lot of code, or hosting you can't change. At that point a rebuild can cost less than continuing to patch it.

Every website we build is designed to load quickly on a phone, with optimised images, minimal scripts and modern hosting. You can see what's included in a business website, or send us your site address and we'll take a look at what's slowing it down.