Render-Blocking Resources
JavaScript and CSS files that block the browser from rendering the page, causing delayed First Contentful Paint and poor user experience.
What You're Seeing
- Blank white page for several seconds before content appears
- Google PageSpeed warns about render-blocking resources
- Poor FCP and LCP Core Web Vitals scores
Why This Happens
- 1Large CSS files loaded in the head without optimization
- 2Synchronous JavaScript in the head blocking HTML parsing
- 3Third-party scripts (analytics, ads, chat widgets) loading before content
- 4No code splitting or lazy loading for JavaScript
How We Fix It
Our senior engineers follow this systematic approach to resolve the issue quickly and permanently.
Identify: Run Lighthouse audit to see which resources are render-blocking.
Defer JavaScript: Add 'defer' or 'async' attribute to non-critical script tags.
Critical CSS: Inline above-the-fold CSS directly in the HTML head, load the rest asynchronously.
Code Split: Break large JS bundles into smaller chunks that load on demand.
Third-Party Scripts: Load analytics and chat widgets after the page is interactive.
Preventing This Issue
Use a build tool that supports code splitting, audit third-party scripts regularly, inline critical CSS as part of your build process, set a performance budget for JavaScript size.
Related Guides
If you're experiencing this issue, you may also want to check these related problems:
- Slow Page Load Speed - Website pages load slowly, causing high bounce rates and poor search rankings. Slow website speed affects user experience, conversions, and SEO performance.
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