How to improve page load time in Webflow and fix performance issues reported by Lighthouse such as render-blocking resources and unused JS?

TL;DR
  • Minify HTML, CSS, and JS in Project Settings and defer non-critical JavaScript by placing scripts in the Footer.  
  • Optimize fonts (limit weights, preload, use WOFF2), compress and lazy-load images in WebP format, and clean unused styles/assets.

To improve page load time in Webflow and address common Lighthouse performance issues like render-blocking resources and unused JS, you can take several strategic steps within the Webflow Designer and Project Settings.

1. Minimize and Defer Unused JavaScript

  • Limit use of third-party embeds and scripts (e.g., chat widgets, ad trackers) unless essential.
  • Remove any unused interactions or components in Webflow as unused IX triggers may still load associated JS.
  • Place custom scripts in the Footer via Project Settings > Custom Code > Footer to defer loading until after HTML rendering.
  • If using large libraries (e.g., jQuery), consider replacing them with native JS or only loading them on needed pages.

2. Eliminate Render-Blocking Resources

  • Enable Webflow’s built-in minification for HTML, CSS, and JS in Project Settings > Hosting.
  • Avoid placing custom CSS in the Head; instead, use Webflow Designer’s Style panel so CSS is bundled and optimized.
  • For third-party styles or fonts, load them asynchronously or defer if possible. Self-host fonts using web-safe formats when suitable.

3. Optimize Fonts

  • Avoid using multiple font families or weights unless necessary.
  • Use Google Fonts with limited weights (e.g., only 400 and 700) and preload key fonts by embedding preload links in the Head.
  • Convert custom fonts to WOFF2 for faster loading.

4. Optimize Images and Use WebP

  • Ensure all images are compressed before upload (use TinyPNG or Squoosh).
  • Use WebP format where possible; Webflow now supports WebP image uploads.
  • In Designer, enable responsive image generations to automatically serve the right image size.
  • Add loading="lazy" to images via the Element Settings panel to defer off-screen loading.

5. Audit and Clean Unused Styles & Assets

  • In the Webflow Designer, go to Style Manager and click “Clean Up” to remove unused classes.
  • Open the Assets panel and delete any unused images, videos, or files.
  • This reduces the total page weight significantly.

6. Use Webflow’s Performance Settings

  • Enable Asset Minification (HTML, CSS, JS) in Project Settings > Hosting.
  • Use Webflow’s built-in responsive and lazy loading techniques; these are enabled by default for most media assets.

7. Use Fewer Webflow Interactions/Animations

  • Excessive animations can add to first contentful paint (FCP) and block interactivity.
  • Minimize page-load animations and only apply animations once content is visible.

8. Audit with Lighthouse & Iterate

  • Use Chrome DevTools > Lighthouse audits and review the Coverage tab for unused CSS/JS.
  • Remove or defer items manually through custom code snippets if Webflow does not provide native controls.

Summary

To boost Webflow performance and resolve Lighthouse issues: minify assetsdefer non-critical JSoptimize fonts and images, and remove unused resources. Regular Lighthouse audits and careful use of custom scripts ensure your site loads faster and ranks better.

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