How can I improve the mobile score above 90 on Google audits for webflow, particularly addressing the issue of First Contentful Paint 3G timing?
TL;DR
- Compress images using WebP format, lazy loading, and proper sizing to reduce load time.
- Remove unused CSS/JS, minimize custom fonts, and defer third-party scripts to avoid render-blocking.
- Simplify DOM structure and limit animations, especially for mobile views.
- Use font-display: swap and preload key assets and CDN connections to speed up visible content rendering.
- Always test on the live, published Webflow site for accurate performance results.
To improve your mobile score above 90 on Google PageSpeed Insights and specifically tackle a poor First Contentful Paint (FCP) over 3G, you need to optimize how quickly visible content is displayed on slow connections.
1. Optimize Image Sizes and Formats
- Use WebP format instead of JPG/PNG for images; it's smaller and faster to load.
- Compress all images using tools like TinyPNG or Webflow’s built-in optimizations.
- Set appropriate image dimensions in Webflow to avoid large images being scaled down via CSS.
- Enable lazy loading by setting images to loading="lazy", so off-screen assets don’t block initial paint.
2. Minimize and Prioritize Critical Assets
- Remove unused CSS and JavaScript. Use Webflow’s “Clean Up” feature under Project Settings > Custom Code if you’ve pasted unused scripts or styles.
- Use fewer custom fonts. Limit to one or two weights/styles per font family.
- Avoid render-blocking resources by deferring third-party scripts (e.g. chat tools, analytics) using the
deferorasyncattribute.
3. Reduce DOM Complexity
- In Webflow, flatten your structure by reducing nested divs and unnecessary wrappers.
- Avoid deeply nested grid or flexbox containers. A simpler DOM means less time to parse and render.
4. Use a Lightweight Webflow Layout
- Start with a minimalist base template or remove unnecessary interactions/animations that delay FCP on mobile.
- Reduce or defer Webflow interactions (e.g. scroll animations) on mobile viewports.
5. Enable Font Display Swap
- Add this in Project Settings > Custom Code > Head:
<link rel="preconnect" href="https://fonts.gstatic.com" crossorigin><style> @font-face { font-display: swap; } </style>- This prevents blocking render until the font is fully loaded.
6. Leverage Preloading and Preconnect
- Preconnect to assets you control (e.g., third-party CDNs):
<link rel="preconnect" href="https://yourcdn.com" crossorigin>- Preload key resources, such as the hero image:
- Add
<link rel="preload" as="image" href="yourimage.webp">inside the<head>section.
7. Audit Third-Party Scripts
- Remove or defer marketing tools like HubSpot, Intercom, or Facebook Pixel unless absolutely necessary.
- Consider loading them after user interaction (e.g. on-click or scroll).
8. Test in Webflow’s Publish Mode
- Don’t rely on the Designer preview. Always test your live, published site, as Webflow minifies and optimizes code only on publish.
Summary
To improve First Contentful Paint on mobile, especially under a 3G simulation, compress images, simplify structure, remove unused scripts, defer third-party assets, and use proper loading techniques for fonts and images. These actions collectively accelerate what’s visible on screen and will push your FCP time below the 2s threshold needed for a 90+ score.