Why is your WordPress site slow? Measuring it and finding the causes

"It loads fast for me" is often true: a fast computer, a good connection and a warm cache. Your visitor's phone tells a different story. Let's measure properly first, then look at the causes.

How to measure

Enter your address in Google's free PageSpeed Insights. You get two tabs: mobile and desktop. The mobile test simulates a slow phone connection, so its score is almost always lower. That's the one that matters: most visitors come from phones.

Look at these two times rather than the score:

• First Contentful Paint (FCP): when anything first appears on screen.
• Largest Contentful Paint (LCP): when the main part of the page (a large image, the headline) appears. This is when the visitor feels the page has loaded.

The most common causes

1. Third-party services

Google Fonts, YouTube, a jQuery CDN, analytics and spam-filter scripts: each means connecting to another server, waiting and downloading. The page may not render until they arrive.

2. Theme and page-builder weight

Multi-purpose themes and page builders load CSS and JavaScript for components the page doesn't even use.

3. Plugins

Each plugin can add its own files and runs on the server for every request. More plugins, heavier pages.

4. Images

Sending a 1600-pixel image where 400 pixels would do on a phone; old formats instead of WebP; loading images that aren't even on the first screen.

5. Background video

An auto-playing video on the first screen (especially via YouTube) is one of the heaviest parts of a page.

Can it be fixed within WordPress?

Partly: caching and optimisation plugins, image compression, self-hosted fonts. But each is another plugin, another setting and another update. We built these into the platform from the start: fonts on our own server, icons inline, images automatically in WebP and the right size, video only on request, no third parties.