Indexing and Coverage, Search Engine Optimization (SEO)

Do Core Web Vitals Affect Mobile or Desktop Rankings?

Modified Date:August 25, 2024

Yes, Core Web Vitals (CWV) affect both mobile and desktop rankings. Google uses these metrics as part of its ranking algorithm to assess user experience on web pages across devices.

However, the Core Web Vitals metrics can differ slightly for mobile and desktop due to factors such as network conditions, device capabilities, and user behavior. Google evaluates the performance of your website separately for mobile and desktop, and the ranking impacts are applied accordingly. Since mobile search has overtaken desktop search in volume, optimizing for mobile CWV is particularly critical.

Here’s a breakdown of strategies to optimize Core Web Vitals for both mobile and desktop:

1. Largest Contentful Paint (LCP) Optimization

Mobile:
- Use responsive images: Serve appropriately sized images for mobile devices to avoid unnecessary loading of large desktop-sized images.
- Mobile-first design: Optimize above-the-fold content for mobile screens by prioritizing important elements for quicker rendering.
- Reduce server response time: Utilize mobile-friendly CDNs and server caching to ensure faster load times.
Desktop:
- Defer non-critical resources: On desktops, there may be more room to display additional content, so defer or lazy-load large background images and videos.
- Optimize desktop-specific layouts: Ensure that your layout structure doesn’t block rendering of important content by minimizing render-blocking resources like CSS and JavaScript.

2. First Input Delay (FID) Optimization

Mobile:
- Minimize JavaScript execution: Mobile devices tend to have slower processors, so reducing the amount of JavaScript can significantly enhance interaction speeds.
- Optimize touch interaction: Make sure that mobile interactions (e.g., touch events, clicks) are handled efficiently, without causing delays due to event handling in JavaScript.
Desktop:
- Optimize for faster CPUs: While desktops usually have more processing power, excessive JavaScript can still cause delays. Minimize the main thread work by splitting up scripts and using web workers.
- Reduce third-party scripts: Similar to mobile, reducing the load from third-party scripts will decrease input delays.

3. Cumulative Layout Shift (CLS) Optimization

Mobile:
- Set explicit size attributes for images and ads: Mobile pages can suffer from layout shifts due to dynamic loading, so ensure that all image, ad, and video elements have defined sizes.
- Use content placeholders: Load placeholders for content that is loading later to prevent layout shifts when the content appears.
Desktop:
- Careful font loading: Desktop views often load custom fonts, which can cause layout shifts. Optimize font-loading performance by using font-display: swap to prevent invisible text during loading.
- Avoid inserting new elements dynamically: Keep the desktop layout stable by avoiding dynamic content injections (e.g., ads or widgets) that can cause layout shifts.

General Best Practices:

Optimize Critical Rendering Path: For both mobile and desktop, optimize the critical rendering path by minimizing CSS, deferring JavaScript, and eliminating render-blocking resources.
Use Lazy Loading: Implement lazy loading for images, videos, and other heavy resources to prevent unnecessary loads and improve performance on both platforms.
Improve Server Response Times: Use techniques such as caching, a faster hosting solution, or a CDN to reduce Time to First Byte (TTFB).