Speed, mobile and conversions

You can have the right message, the right offer and great reviews, and still lose visitors before they see any of it. A slow page, a button that's hard to tap, or a pop-up that covers the screen on a phone all stop people before your content gets a chance. This guide connects speed and mobile usability to conversions, and lists the fixes worth prioritizing.

Why speed affects conversions

Every moment a visitor waits is a moment they might leave. The effect is strongest at the start, before anything useful appears, and on the steps closest to a decision, such as a checkout or a contact form.

Google has published case studies over the years linking faster pages with better business results, and its web.dev site collects many of them. The exact numbers vary by site, so treat them as direction rather than a promise. The principle is consistent: faster and more stable pages make it easier for people to do what they came to do.

The three Core Web Vitals in plain English

Google measures real visitors' experience with three metrics, called Core Web Vitals. Google's published "good" thresholds are:

Metric	What it measures	Good
Largest Contentful Paint (LCP)	How quickly the main content appears	2.5 seconds or less
Interaction to Next Paint (INP)	How quickly the page responds when someone taps or clicks	200 milliseconds or less
Cumulative Layout Shift (CLS)	How much the layout jumps around while loading	0.1 or less

Each one maps to a conversion problem:

Slow LCP: the visitor stares at a blank or half-built page and leaves.
Slow INP: they tap "Add to cart" or "Send" and nothing seems to happen, so they tap again or give up.
High CLS: they go to tap a button and the page shifts, so they tap an ad or the wrong link instead.

See Core Web Vitals explained for the full picture and Measuring your speed for how to check yours.

Mobile: where conversions are often lost

Many visitors see your site on a phone first, even if they later convert on a computer. Check your own analytics (the Tech reports in Google Analytics) to see your device split.

Common mobile conversion blockers:

Tap targets too small or too close together. Buttons and links should be easy to hit with a thumb.
Text too small to read without zooming.
Pop-ups that cover the content, especially immediately on arrival. Google's guidance on page experience specifically mentions avoiding intrusive interstitials.
The call to action buried below a large image and several paragraphs.
Phone numbers that aren't tappable. On mobile, a tap-to-call link is often the easiest conversion of all.
Forms that are painful on a phoneTiny fields, wrong keyboards, fields that zoom the screen, or dropdowns with dozens of options.
Sticky bars that take up half the screen, such as cookie banners, chat widgets and promotional bars all at once.

A quick mobile conversion check

Use your own phone, on mobile data, not office Wi-Fi. Open your homepage and one key service or product page.

Time how long until you can read the headline and see the main button. If you find yourself waiting, so are your visitors.

Try to convert. Tap the phone number. Fill in the form. Add something to the cart. Note every moment of friction.

Count the overlays. Cookie banner, chat bubble, pop-up, sticky header. How much of the screen is left for content?

Run PageSpeed Insights on the same pages, and look at the mobile results.

Fixes that usually matter most

Most of these are covered in more depth in the performance checklist.

Compress and correctly size images, especially the large one at the top. This is often the single biggest LCP improvement. See Images and speed.
Remove or delay third-party scripts you don't need: old tracking tags, unused chat tools, social widgets. Each one costs load time.
Reserve space for images, embeds and ads so the layout doesn't jump.
Limit plugins and heavy page-builder effects on key pages. See Plugins and speed.
Use good hosting and caching. See Hosting and speed.
Simplify the mobile layout around one clear call to action.
Delay pop-ups, or show them only on exit intent on desktop, and make them easy to close.

Prioritize by conversion, not by score

A perfect PageSpeed score on your About page matters less than a decent experience on the pages that make money. Start with:

The pages with the most entrances from search and ads.
Your contact, booking or checkout pages.
Your main service or product pages.

And remember a score is a lab test. Real-visitor data (the "field data" in PageSpeed Insights and the Core Web Vitals report in Search Console) shows what customers actually experience.

Frequently asked questions

My site feels fast to me. Why do tools say it's slow?

You're probably on a fast computer and connection, and your browser has cached the site. Many visitors are on mid-range phones on mobile networks seeing it for the first time. Test the way they do.

Is a separate mobile site a good idea?

Generally not any more. A single responsive site that adapts to screen size is the standard approach and is simpler to maintain. See Mobile-friendliness & SEO.