Oversized images slowing a website: how to spot them

Open the website of a local landscaper, a bakery or a dental practice on your phone, on mobile data, and watch what happens. Often the text arrives quickly and then the page sits there while a large photograph slowly draws itself from the top down. That wait is usually oversized images slowing a website that is otherwise perfectly sound.

It is one of the easiest problems to find and one of the easiest to explain to a business owner, which makes it a good first thing to check.

How it happens

Nobody sets out to build a slow page. The owner takes a photo of their finished kitchen on a modern phone, uploads it to the site, and the site shows it at a few hundred pixels wide. The browser still has to download the original file, which can be many times larger than the space it fills. Multiply that by a gallery of twenty photos and the page becomes heavy without anyone noticing.

Site builders and WordPress themes sometimes resize images for you, and sometimes they do not. A full-width banner image uploaded straight from a camera is a common culprit. So is a logo saved as a large photograph file when a small vector or compressed version would do.

Spotting it in a couple of minutes

1. Run a speed test. Google's PageSpeed Insights will often flag images that are larger than they need to be. We cover reading those results in how to test website speed for a client.
2. Look at the network panel. In your browser's developer tools, reload the page and sort the requests by size. If a single image file is far bigger than everything else, you have found your answer.
3. Compare file size to display size. Right-click an image, open it in a new tab and check its dimensions. If a photo showing as a small thumbnail is thousands of pixels wide, it is oversized.
4. Check the format. Large PNG files used for ordinary photographs are a frequent sign. Photographs generally compress much better as JPEG or as newer formats such as WebP.
5. Scroll the page. Images far down the page that load immediately, rather than as you scroll, suggest nothing is deferring them.

What the fix usually involves

For most small sites the fix is not dramatic. Resize images to roughly the size they are displayed at, compress them, and serve a modern format where the platform supports it. Make sure images below the fold are loaded lazily. On WordPress there are plugins that handle much of this, and most site builders have settings for it, though how well they work varies, so test the result rather than assuming.

It is also worth setting width and height on images so the page does not jump around as they load. That is a separate annoyance for the visitor, but it often turns up alongside the same problem.

One caution. Speed scores are a guide, not a verdict. A page can score poorly for several reasons at once, such as heavy scripts, an overloaded theme or slow hosting. Look at what is actually loading before you promise a number. Our post on why a website is slow and what it costs local businesses goes through the other usual suspects.

Raising it with a business owner

Skip the jargon. Nobody needs to hear about compression ratios. Say what you saw: that the homepage photo takes a noticeable moment to appear on a phone, and that a smaller version of the same picture would look identical and load sooner. If you have a screenshot or a short list of the three biggest files, include it. That is concrete, fair, and easy to check for themselves.

Do not overstate what it costs them. You can say a slow page is more likely to frustrate visitors. You cannot say how many enquiries they lose, because you do not know.

Finding sites worth checking

Checking one site by hand is easy. Checking thirty in a town is a different job. Patchscout searches a business type in a UK location, audits each site it finds for speed, SEO, mobile and SSL, and scores how good a fit each business is as a prospect. Our system then drafts an outreach email in your own voice, grounded in what the audit actually found, which you send from your own mailbox.

Whichever way you find them, the oversized image is a good opening observation: specific, verifiable and kind. It says you looked at their site properly, which is the whole point of the first email.