How can I improve my page speed in Webflow, specifically regarding render-blocking resources and unused JS? My site's mobile speed is slow due to Webflow sending one large JS file instead of splitting it into smaller packages.

Improving mobile page speed in Webflow requires minimizing render-blocking resources and optimizing unused JavaScript, especially since Webflow bundles much of its scripts into a single large file. Here's how to improve performance within Webflow’s limitations.

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1. Minimize Use of Webflow Interactions and Components

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• Reduce animations and interactions that rely on Webflow’s native IX2 engine, which heavily contributes to the global JavaScript bundle.
• Avoid unnecessary components like sliders, tabs, and dropdowns if you’re not using them—Webflow still loads their scripts even if they aren’t used efficiently.

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2. Defer or Delay Custom Code and Scripts

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• Use custom code embeds responsibly by adding defer or async to any external JS scripts where possible. This prevents them from blocking rendering.
• Load third-party scripts (e.g., chat widgets, analytics) after page load using tools like Google Tag Manager or by wrapping code in setTimeout() or requestIdleCallback().

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3. Optimize Fonts and Reduce FOUT

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• Limit the number of fonts and weights you use. Every font weight adds to your render-blocking resources.
• Enable font-display: swap via custom CSS to allow faster text rendering.

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4. Enable WebP or Compressed Image Formats

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• Convert heavy image assets to WebP for reduced payload.
• Use Webflow’s responsive image feature and set loading="lazy" for images below the fold.

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5. Host Scripts Externally When Possible

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• If you use custom JavaScript (not interaction-based), consider hosting it externally with HTTP/2 and defer enabled to avoid bloating Webflow’s built-in bundle.

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6. Use Page Load Split Techniques (Manual)

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• Webflow doesn’t support code splitting out of the box. However, you can create “light” landing pages using exported Webflow code, manually removing unused JS.
• Alternatively, use client-side routing/loading frameworks outside Webflow for high-performance use cases.

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7. Audit with Lighthouse and Chrome DevTools

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• Use Chrome DevTools > Coverage tab to identify unused JS and CSS.
• Use Lighthouse performance audits to pinpoint specific render-blocking scripts and strategy improvements.

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8. Consider Webflow Enterprise or External Hosting

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• For advanced control, consider exporting Webflow code and hosting it on a custom frontend with code splitting (e.g., Next.js or Astro).
• Webflow Enterprise gives more control over performance optimizations, but this isn't typically available on standard plans.

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Summary

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To speed up your Webflow site's mobile performance and address render-blocking JS and unused JavaScript, reduce Webflow native feature usage, defer non-critical scripts, optimize fonts and images, and audit with developer tools. For significant gains, consider exporting and optimizing your code manually outside of Webflow.