Core Web Vitals & Page Speed: How They Impact UK Business Revenue

What Are Core Web Vitals (in Plain English)?

Forget the technical jargon for a second. Google's Core Web Vitals (CWV) are simply a set of metrics to answer three questions from a user's perspective:

1. How fast does it load? (LCP)
2. How fast does it respond to my clicks? (INP)
3. Is it stable, or does it jump around as it loads? (CLS)

In 2025, Google uses these scores as a significant ranking factor. Why? Because users *hate* slow, janky websites. And what users hate, Google hates. Improving your CWV scores is no longer an option; it's essential for both SEO and user trust.

The Business Impact: The £ Cost of a Slow Site

This isn't just about rankings. It's about revenue. The data is clear:

• A 1-second delay in mobile load time can impact conversion rates by up to 20% (Google).
• Deloitte found that a 0.1-second improvement in site speed led to an 8.4% increase in conversions for retail clients.

Let's do the maths for a UK business:

Your e-commerce site gets 20,000 visitors a month, your conversion rate is 2%, and your average order is £75. You make £30,000/month.

Your site is 1.5 seconds too slow. Fixing it boosts conversions by just 10% (a conservative estimate). That's an extra £3,000 every single month, or £36,000 per year. Suddenly, investing in a performance optimisation service makes perfect financial sense.

Use our Speed Impact Calculator to run your own numbers.

A Developer's Look at LCP, INP, and CLS

1. LCP (Largest Contentful Paint)

• What it is: The time it takes for the *largest* element (usually a hero image or text block) to become visible.
• What causes a poor score: Uncompressed images, slow server response (bad hosting), and render-blocking JavaScript/CSS.
• How we fix it: We compress and serve images in Remove WebP format, use a CDN (Content Delivery Network) with UK servers, and defer non-critical scripts.

2. INP (Interaction to Next Paint) - The New Standard

• What it is: Measures the *total time* from when a user clicks a button (e.g., "Add to Cart") to when the page visually responds. This replaced FID in March 2024.
• What causes a poor score: Bloated JavaScript. This is the #1 culprit. Too many WordPress plugins or Shopify apps running complex scripts will freeze the main thread, making your page feel broken.
• How we fix it: This is a true developer task. We audit and remove unnecessary plugins/apps, refactor code, and delay script execution until after the user needs them.

3. CLS (Cumulative Layout Shift)

• What it is: Measures how much your content "jumps" around as the page loads. It's infuriating when you try to click a button, and an ad loads, pushing it down.
• What causes a poor score: Images without defined dimensions (width and height tags), late-loading ads, or fonts loading in.
• How we fix it: We ensure all images and containers have set sizes in the CSS/HTML, so the browser "saves the space" for them before they load.

How to Diagnose Your Scores (The 2-Minute Test)

1. Go to PageSpeed Insights.
2. Enter your website URL.
3. Toggle between the Mobile and Desktop reports. (Remember, Mobile is what Google ranks you on).
4. Look at your "Core Web Vitals Assessment". If it's "Failed" (red or amber), you have a problem.
5. You can also check the "Core Web Vitals" report in your Google Search Console for a site-wide average.

Interpreting the "Opportunities" section can be highly technical. It might say "Reduce unused JavaScript," but you need a developer to know *which* JavaScript is safe to remove.

Actionable Speed Fixes for UK Businesses

While deep fixes require a developer, here are the "quick wins" you can look into:

• Get Better Hosting: If your TTFB (Time to First Byte) is high, your server is slow. Move to a quality UK-based host.
• Install a Caching Plugin: (WordPress) WP Rocket or FlyingPress are the best. (Shopify) This is handled for you, but theme choice matters.
• Use a CDN: A Content Delivery Network stores copies of your site worldwide. For a UK audience, this means images load from a London or Manchester server, not one in Texas.
• Optimise Images: Use a plugin like ShortPixel. No image should be over 200kb.
• Do a Plugin/App Audit: Deactivate and delete *any* plugin or app you aren't actively using. Each one slows you down.

Stop Guessing. Start Improving.

Your Core Web Vitals are a direct indicator of your site's health and its ability to generate revenue. Stop letting a slow, frustrating experience cost you sales.

Our Page Speed Optimisation service goes beyond plugins. We profile your code, find the real bottlenecks, and implement lasting fixes. Request a free, no-obligation audit today and see how much faster your site—and your business—could be.