Site Speed Fix Analyzer

Speed work goes wrong when people optimise a number instead of an experience. The metrics that matter are the Core Web Vitals: Largest Contentful Paint, which is how long the biggest visible element takes to appear, Interaction to Next Paint, which is how quickly the page responds when someone taps, and Cumulative Layout Shift, which measures content jumping around while it loads. A high score with poor vitals is worth nothing, and improving vitals almost always improves the score as a side effect.

Test on a throttled mobile connection, not on your office desktop, and test a page that matters rather than only the homepage. Run each test twice: the first run often measures a cold cache, and the second tells you what a returning visitor experiences. Note the difference between the two, because a large gap points at server response time rather than at front-end weight.

In practice most slow WordPress sites are slow for one of four reasons, and they are worth checking in order of impact. First, uncompressed images: an unresized photograph straight from a phone can be several megabytes and is very often the Largest Contentful Paint element. Second, server response time, visible as a long time to first byte, which usually means no page caching, an overloaded shared host, or a plugin running heavy queries on every request. Third, too many plugins loading assets on every page, including on pages where their functionality is not used. Fourth, render-blocking CSS and JavaScript in the head that delays the first paint.

Fixing them in that order gives the largest improvement for the least risk. Resize and convert images to WebP, then let a caching plugin serve static HTML, then audit which plugins load assets sitewide, and only then start deferring scripts. Reversing this order is how people end up with a broken layout and a barely faster site.

Aggressive optimisation settings are the leading cause of a site that scores well and looks wrong. Combining and minifying CSS can break layouts when files depend on load order. Deferring or delaying JavaScript often breaks sliders, menus and forms, and the damage is easy to miss because it only shows on interaction. Lazy loading applied to the hero image makes Largest Contentful Paint worse rather than better, since the browser deliberately waits before fetching exactly the element you are being measured on.

Change one setting at a time and check the site properly after each one, including a form submission, the mobile menu and the cart if you have one. Keep the hero image eagerly loaded and give every image explicit width and height attributes so the browser reserves space and layout shift stays near zero. And remember that caching plugins hide your changes from yourself; purge the cache before concluding that an adjustment made no difference.