How to · Guide gratuit
A slow website costs you customers.
Someone clicks your site, and it loads... and loads. On a phone, those people don't wait for you: they back out and click the next one. Good news: the cause is almost always the same, and it gets fixed without rebuilding your site.
- Test your site on PageSpeed Insights. Free, it's Google's official tool.
- Look at the MOBILE score. That's where your customers are, and where it hurts.
- Aim for 90 and up. Under 50, you're losing people on every visit.
- Oversized images are cause number one. By a mile.
- Never upload the phone photo as-is. Resize before putting it online.
- Re-test after every change. The score moves right away.
01Why speed is money
Two reasons. First: your visitors. On mobile, every second of waiting peels some of them off, and the ones who leave go to your competitor. Second: Google measures your site's speed and uses it in ranking. A slow site starts with a strike against it, before anyone even talks about content.
02The test: two minutes, free
Go to PageSpeed Insights (search it on Google, it's the official tool), paste your site's address, and wait for the report. You get two scores out of 100: mobile and desktop.
Look at mobile first. It's always the worse of the two, and it's where most of your customers visit you. Above 90, you're in business. Between 50 and 90, there's easy ground to gain. Under 50, your site is chasing people away every day.
03Cause number one: oversized images
In almost every small business site I test, the culprit is the same: phone photos uploaded exactly as they came out. A modern phone photo is 4,000 pixels wide and weighs several megabytes. Your site displays it in an 800-pixel box: the visitor downloads five times too much data for nothing, on their phone plan.
- Resize before uploading: around 1,600 pixels wide for a big image, less for a thumbnail.
- Compress. Free tools like Squoosh do it right in your browser, nothing to install. The difference is invisible to the eye, and the page weighs a lot less.
- The modern format (WebP) weighs less than old JPEG at equal quality, if your tool offers it.
A full home page should weigh less than ONE uncompressed phone photo. Keep that as your rule of thumb.
04Load only what's visible
Your visitor lands at the top of the page: why would their phone immediately download the twelve photos at the bottom? Lazy loading fixes that: images further down load only when someone scrolls to them. It's a built-in web feature now, and most platforms offer it. Make sure it's on.
05Sites loaded like Christmas trees
The other big cause: plugins and gadgets piling up. Every module added to a builder site (counters, carousels, pop-ups, tracking tools) brings its own code, which every visitor downloads. One by one they're small; stacked, they smother the site. Keep only the ones that actually do something. If you're not sure a module earns its place, remove it and watch your score climb.
06The full checklist
- Mobile PageSpeed score known (and written down somewhere)
- All photos resized before uploading
- Compression run on the heaviest existing images
- Lazy loading on for images lower down the page
- Non-essential plugins removed
- Re-test after every change
Published July 14, 2026