Why mobile performance matters

• Mobile-first indexing: Google uses the mobile version of a page to rank it.
• Slower connections: phones often load pages over mobile networks, so heavy pages hurt more.
• Smaller screens: layouts, buttons and text that work on a desktop can be unusable on a phone.

Measure first

Run your key pages through PageSpeed Insights and look at the mobile results. In Search Console, the Core Web Vitals report shows which groups of pages pass or fail, based on real visitors.

1. Use a responsive layout

A responsive theme adapts to every screen width. Make sure every page has the viewport tag in its head:

<meta name="viewport" content="width=device-width, initial-scale=1">

• Use text of at least 16 pixels for body copy, so visitors do not need to zoom.
• Make buttons and links big enough to tap, with space between them.
• Avoid pop-ups that cover the content on small screens.

2. Get images right

• Resize images to the size they are shown, and let your CMS create smaller versions for phones.
• Serve WebP or AVIF where possible; they are much smaller than JPEG and PNG at the same quality.
• Lazy-load images below the first screen, but not the main image at the top, which affects LCP.
• Set width and height on images, so the layout does not jump while they load (CLS).

3. Reduce JavaScript and fonts

Heavy scripts are the main cause of poor INP on phones. Remove plugins and tracking scripts you do not need, delay non-essential scripts until after the page loads, and use only one or two web font families with font-display: swap.

4. Speed up the server response

• Turn on page caching, so pages are served ready-made instead of built by PHP for every visit.
• Use the newest PHP version your site supports, and an object cache such as Redis for dynamic sites.
• Keep the database lean. See our database performance guide.

5. Use a CDN

A CDN serves images, CSS and JavaScript from locations close to your visitors, which cuts load time for visitors far from your server. Our CDN guide explains the options, and our Cloudflare and cPanel guide covers a common setup.

6. Keep navigation simple

Use a short menu that collapses on small screens, a visible search box on content-heavy sites, and clear calls to action near the top of the page. Test forms on a real phone: fields should use the right keyboard, such as the number pad for phone numbers.

What about AMP?

AMP is no longer needed for good mobile rankings or for Google’s Top Stories. A fast responsive site that passes Core Web Vitals is the better long-term choice, and it avoids maintaining two versions of every page.

Mobile checklist

• ✓ Viewport tag present on every page.
• ✓ Core Web Vitals pass in Search Console.
• ✓ Images resized, compressed and in modern formats.
• ✓ Page caching on, and a CDN for static files.
• ✓ Buttons, text and forms comfortable to use on a phone.

For more speed work, see our site speed guide.