How can I address JavaScript-related issues with my Webflow site to improve its speed, particularly in regards to unused JavaScript, execution time, and minimizing main-thread work, considering that I have no experience with JS or custom code? I have already tried minifying HTML, CSS, and JS, as well as cleaning up unused classes, but these tweaks resulted in a slightly worse performance score.

You're experiencing performance issues on your Webflow site due to JavaScript-related inefficiencies, like unused JS, long execution times, and main-thread blocking—despite already optimizing HTML, CSS, and classes.

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1. Audit Your Installed Webflow Components

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• Review third-party scripts, like live chat, analytics, tracking pixels, or social widget embeds. These are common sources of excessive or unused JavaScript.
• Temporarily disable or remove one third-party integration at a time and run a Lighthouse or PageSpeed Insights audit after each change to see which ones impact load and execution time.
• Popular culprits include tools like Hotjar, Intercom, Facebook Pixel, and external sliders or galleries.

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2. Reduce Built-In Webflow Interactions

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• Open the Interactions panel in Webflow and look for complex scroll or hover animations, which can add to JavaScript execution time.
• If possible, simplify or remove interactions, especially those applied site-wide or tied to scroll events. These add listeners that block the main thread.
• Avoid multiple nested animations or overly smooth transitions if performance is a priority.

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3. Use Webflow’s Built-in Lazy Load & Asset Optimization

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• Images and background videos should have lazy loading enabled. Webflow does this automatically via loading="lazy" on compatible assets—but you can confirm by inspecting the published site.
• CMS collections with lots of dynamic content (like blog pages) should be paginated to reduce JS and layout stress on the browser.

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4. Limit Use of Lottie Animations and Large Components

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• Lottie and similar JSON-based animations rely on additional JavaScript to render. If you're not using them for essential interactions, consider replacing them with static visuals or simpler animations.
• Also, avoid heavy components like full-page sliders with multiple images, animations, or autoplay videos.

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5. Delay or Defer Third-Party JS (via Webflow Settings)

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• Go to Project Settings > Custom Code, and move any third-party scripts from Before </head> to Before </body>, which simulates delayed loading.
• While Webflow doesn't give fine control over JS loading behavior without actual scripting, repositioning scripts to the footer region can help defer execution visually.

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6. Test with PageSpeed & Prioritize Largest Contentful Paint (LCP)

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• Use Google PageSpeed Insights or Lighthouse in Chrome DevTools to identify which scripts or elements are affecting LCP and main-thread time.
• Focus on optimizing or replacing the elements flagged—often video headers, large sliders, or hero banners carry too much JS or animation weight.

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7. Duplicate the Project and Strip It Down for Testing

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• Create a duplicate version of your Webflow site and remove one feature or script block at a time. This helps isolate which elements cause performance issues without damaging the live site.

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Summary

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To reduce JavaScript impact without coding skills, focus on removing third-party scripts, simplifying interactions, lazy loading assets, and deprioritizing heavy components like Lottie or autoplay videos. Use Webflow’s built-in tools and strategic testing to isolate what’s causing the performance hit.