SPEEDING UP A WORDPRESS SITE: THE COMPLETE GUIDE, IN THE ORDER THAT MATTERS

A slow WordPress site isn't inevitable, it's an accumulation. Here are the ten actions that count, in the order I do them for my clients, with what each one delivers and what it can break.

0. Measure before touching anything

Three figures are enough: the server response time (TTFB), the total weight of the homepage, and the PageSpeed mobile score. Write them down. You'll compare them at the end. Without a starting measurement, you'll never know what worked, and you'll install one more plugin "just in case".

1. Images

The first item, in nine sites out of ten. A photo straight from the phone weighs 3 to 5 MB and is displayed in a 400-pixel frame. Three actions: resize to the size actually displayed (twice that for high-density screens), convert to WebP or AVIF, lazy-load everything below the fold. WordPress has handled the last two since version 6; the first requires reprocessing the media library or letting a script do it. Usual gain: 60 to 80 percent of the page weight.

2. Page caching

Without caching, WordPress queries the database and assembles the page on every visit. With it, it serves a ready copy in a few milliseconds. It's the most spectacular gain on response time, and the most dangerous if configured badly: a cache that keeps one customer's cart for the next, a form whose token has expired, an account page served to everyone. Exclude the cart, checkout, account, URLs with parameters, and test with a real purchase.

3. Plugins

Every plugin adds its stylesheets and scripts to every page, even where it serves no purpose. List them, deactivate what nobody uses, replace the bloated ones with a few lines of code. A site with forty plugins loads a hundred files; the same site with twelve loads thirty. Beware of performance plugins themselves: stacked, they contradict each other.

4. Third-party scripts

Live chat, ad pixel, map, embedded video, reviews, tag manager: each loads hundreds of kilobytes from a server you don't control, and blocks rendering. Keep what pays, load the rest after the content appears or on the visitor's first gesture, and replace the embedded YouTube video with a thumbnail that only loads the player on click.

5. Fonts

Three Google Fonts families in six weights is half a second of waiting on mobile before the text shows, and a layout that jumps when they arrive. Two families maximum, hosted on your server, preloaded, with a fallback font of the same dimensions so that nothing moves.

6. The theme and the page builder

"All-in-one" themes and visual builders load animations, carousels and libraries of which you use only a fraction. You don't change theme to go faster, you deactivate what isn't used: builder modules, icons, animations, demo scripts. If the theme is beyond saving, a dedicated theme written for your site weighs five times less; that's a light redesign, not a new site.

7. The database

Thousands of post revisions, auto-drafts, spam comments, data left behind by deleted plugins. Cleaning and optimising the tables makes the admin snappier and non-cached pages faster. To be done with a tested backup taken just before.

8. Hosting

If the server takes 800 milliseconds to respond before sending the first line, no site optimisation makes up for it. A good French host responds in under 200 milliseconds, with a recent PHP version and server-side caching. Changing host is sometimes the only action needed, and sometimes pointless: the starting measurement decides.

9. The PHP version

Going from PHP 7.4 to 8.3 speeds up execution by 20 to 40 percent without touching the site, provided the plugins are compatible. It's a maintenance operation, not development: test on a copy, switch, watch the error logs for a week.

10. A content delivery network (CDN)

Useful if your customers are far from the server or if the site is very busy. Pointless for a local showcase site hosted in France and visited from the French Riviera. Don't start there.

What it gives

On the sites I have taken over, actions 1 to 5 are generally enough to go from a mobile score of 40 to over 85, in a week, without a rebuild. Actions 6 to 9 take it beyond 90. Measure at the end, with the same tools as at the start, and note the date: a site slows down as soon as you add a plugin or a video. If you'd rather someone take care of it and commit to the result, that's exactly the Slow website service.

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