Why Is My Website Slow? Core Web Vitals Explained for Non-Developers

"My site feels slow" is a real complaint with no number attached to it. Google’s answer to "how fast is fast enough" is three specific, measurable metrics called Core Web Vitals. Here’s what they actually measure, without the developer jargon.

Largest Contentful Paint (LCP)

How long it takes for the biggest visible thing on the page, usually a hero image or main headline, to finish loading. This is the metric closest to what a visitor actually experiences as "did the page load yet." A large, unoptimised hero image is the single most common cause of a bad LCP score.

Interaction to Next Paint (INP)

How quickly the page responds once someone actually taps a button or a link. A page can look fully loaded and still feel broken if tapping "Add to Cart" takes a beat too long to register, usually because too much JavaScript is competing for the browser’s attention at once.

Cumulative Layout Shift (CLS)

Whether content jumps around while the page is still loading, a button shifting down just as you’re about to tap it, because an image above it finished loading late and pushed everything beneath it. It’s the most physically annoying of the three, and usually the cheapest to fix, once you know to look for it.

Why this matters beyond "it feels slow"

These three metrics are part of what Google calls Page Experience, and they factor into ranking, not just user comfort. On South African mobile networks specifically, where connection quality varies a lot more than on a fixed office fibre line, a site that scores badly on Core Web Vitals in a lab test is usually a genuinely rough experience for a real visitor on the street, not just a number.

The usual causes

• Unoptimised images: a photo straight off a phone camera, uncompressed, serving five times the file size the page actually needs.
• Too many render-blocking scripts: chat widgets, tracking pixels, and font loaders all fighting to load before the page can finish painting.
• Hosting that’s slow to respond in the first place, no amount of frontend optimisation fixes a server that takes too long to answer.
• Third-party embeds, a video player, a review widget, a booking calendar, each one adding its own load time on top of the page’s own.

How to see your own numbers

Guessing is unnecessary. The free SEO Checker on this site pulls real Google PageSpeed data for performance, SEO, and accessibility, the same underlying data Google itself uses, not a rough estimate. Run your own site through it and see the actual score, not a feeling.

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