Performance
Website speed and your ad budget: Core Web Vitals in plain language
Three numbers Google uses to judge your pages, why they affect what you pay for traffic, and the short list of fixes that usually sorts them out.
The short version
- Google measures real visitors’ experience with three numbers: loading, responsiveness and visual stability.
- Slow pages lose visitors before they see your offer, and can raise what you pay per click.
- Most slowness comes from a short list of causes that can be fixed without a rebuild.
The three numbers
| Measure | What it means | Good |
|---|---|---|
| LCP Largest Contentful Paint | How long until the main content appears | 2.5 seconds or less |
| INP Interaction to Next Paint | How quickly the page reacts to a tap or click | 200 milliseconds or less |
| CLS Cumulative Layout Shift | How much the page jumps around while loading | 0.1 or less |
Google collects these from real Chrome users and judges a page by how it performs for most visits, on phones as well as computers.
Why it matters when you pay for traffic
Two reasons. First, people leave slow pages: every extra second before the content appears loses some of the visitors you have already paid for. Second, Google Ads rates landing page experience as part of its Quality Score. A better score can mean a lower cost per click and a better position for the same bid.
The usual causes
- Images far larger than the space they fill, in old formats.
- Too many scripts: chat widgets, trackers and sliders, each adding weight.
- Page builders and plugins that load everything on every page.
- Fonts pulled in from several places.
- Slow hosting, or no caching.
- No space reserved for images and banners, so content jumps as they load.
What fixing it looks like
- Measure on a real mid-range phone, not a developer’s laptop.
- Fix the biggest cause first. It is often images or one heavy script.
- Add caching and compression on the server.
- Remove what nobody uses.
- Measure again, and keep the before-and-after numbers.
Most sites improve markedly without being rebuilt.
How to check your own site
Search for “PageSpeed Insights”, enter your address and look at the mobile result. The section at the top, taken from real visitors, is the one that counts. If any of the three numbers is red or amber, there is money to save.