What can I do to improve my website's loading speed in Webflow, particularly in terms of optimizing images for mobile devices and reducing total blocking time?

To improve your Webflow website's loading speed, especially for mobile devices and to reduce Total Blocking Time (TBT), you need to optimize image assets and streamline your interactions and third-party scripts.

1. Optimize Images for Mobile Devices

• Use WebP Format: Webflow automatically compresses images, but convert large JPEG or PNG files to WebP format before uploading for better compression without quality loss.
• Set Responsive Image Sizes: Use responsive images by enabling Webflow's responsive image generation. Webflow creates multiple sizes of each image for different breakpoints.
• Use the Correct Display Size: Don’t insert high-resolution images where smaller ones are needed. Scale images according to their actual display dimensions on mobile devices.
• Enable Lazy Loading: Webflow enables loading="lazy" by default for images, but ensure none are excluded from this unless critical for above-the-fold content.
• Use Background Gradients or SVGs: Replace complex image backgrounds with CSS gradients or SVGs when possible.

2. Reduce Total Blocking Time (TBT)

• Minimize Use of Heavy Interactions: Limit complex Webflow interactions and animations, especially on page load. Replace them with simpler transitions where possible.
• Defer Non-Critical Scripts: Remove or defer third-party scripts (e.g., chat widgets, analytics) that aren’t essential at page load. Use Google Tag Manager to control when scripts load.
• Avoid Overuse of Fonts and Weights: Only load the font weights and styles you actually use. Webflow projects often load multiple weights by default.
• Limit Embedded Content: Minimize the use of iframes, video embeds, and interactive maps that block rendering. Use thumbnails and load embeds on click if possible.
• Keep Lottie Animations Efficient: Use compressed Lottie files (via bodymovin with gzip) and set them to play only when needed—avoid autoplay on load unless absolutely necessary.
• Audit with Lighthouse: Use Chrome’s Lighthouse audit to measure TBT and pinpoint the scripts or elements delaying interactivity.

3. Use Webflow's Built-In Performance Tools

• Enable Asset Minification: In Project Settings > Hosting, enable Minify HTML, CSS, and JS options.
• Remove Unused Styles and Components: Regularly clean up unused classes, interactions, and styles in the Style Manager and the Interactions panel.
• Use Fewer CMS Items on Load: Limit the number of dynamically loaded CMS items per page, especially for mobile views. Use pagination or “Load more” features.

Summary

To boost your Webflow site's mobile loading speed and reduce Total Blocking Time, optimize images with responsive, compressed formats, lazy-load non-critical content, avoid heavy interactions, and minimize script usage. Regularly audit your site with Lighthouse and clean up unused assets and styles for a leaner, faster experience.