LCP
Largest Contentful Paint
9.9s
Poor
Good: < 2.5s
Measures how long it takes for the main content to appear on screen
Reduce Unused JavaScript Bundles
How to optimize youtube.com
Reduce Unused JavaScript Bundles
High Impact+22 points estimated
Why It Matters
616 KiB of unused JavaScript is blocking render and delaying LCP by 1.45 seconds.
How to Fix
Implement code splitting to load only essential JavaScript for initial page render. Use dynamic imports for player functionality that loads after user interaction. Split the large base.js bundle (437KB) into smaller chunks and lazy-load video player components. Analyze bundle with webpack-bundle-analyzer to identify unused modules.
0Needs Improvement
What This Score Means
A score of 56 falls in the "Needs Improvement" range (50-89). While it is better than poor (0-49), you should aim for 90+ to provide an optimal user experience and maximize SEO benefits.
This site is slower than approximately 35% of similar sites. The main issues affecting performance are image optimization, JavaScript execution time, and layout stability.
Addressing these issues could improve your conversion rate by 15-20% and boost your search engine rankings.
Core Web Vitals Analysis
INP
Interaction to Next Paint
194ms
Good
Good: < 200ms
Measures how quickly the page responds to user interactions
CLS
Cumulative Layout Shift
0.00
Good
Good: < 0.1
Measures visual stability - how much content shifts during page load
AI Performance Analysis
YouTube's mobile site is performing poorly with a score of 56/100, indicating significant performance issues that hurt user experience. The biggest problem is excessive page redirects that waste 1.5 seconds before the page even starts loading, combined with massive amounts of unused JavaScript (616 KB) and CSS (181 KB) that slow down content rendering. The site takes an alarming 9.9 seconds for the main content to appear and 12.4 seconds to become fully interactive, which is far too slow for modern web standards. YouTube could dramatically improve performance by eliminating redirects, removing unused code, and optimizing their resource loading strategy.
Other Optimization Recommendations
Eliminate Multiple Page Redirects
High Impact+25 points estimatedWhy It Matters:
Three consecutive redirects are adding 1.54 seconds of unnecessary delay before any content can load.
How to Fix:
Update all internal links to point directly to https://m.youtube.com/ instead of youtube.com or www.youtube.com. Configure server to redirect non-mobile traffic directly to the mobile domain without intermediate redirects. Test redirect chains using tools like Redirect Checker to ensure single-hop redirects.
Remove Unused CSS Rules
High Impact+18 points estimatedWhy It Matters:
181 KiB of unused CSS is delaying First Contentful Paint by 600ms and blocking critical rendering.
How to Fix:
Use PurgeCSS or similar tools to remove unused styles from the main stylesheet. Split CSS into critical above-the-fold styles and defer non-critical player styles. Inline critical CSS directly in the HTML head and load remaining styles asynchronously after page render.
Keep Your Site Fast After Optimization
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Related Performance Analyses
More Generic Speed Tests
Generic Performance Resources
Eliminate Render-Blocking CSS
Critical CSS is blocking First Contentful Paint by 150ms, delaying initial page rendering.
Add fetchpriority=high to LCP Image
The LCP image lacks priority hints, preventing the browser from optimizing its loading sequence.
Optimize Image Compression and Sizing
Images are oversized and poorly compressed, causing 2.9 second LCP delay and wasting 670 KiB.
Fix Forced Reflow Issues
JavaScript in header.js is causing 26ms of forced reflows, creating layout thrashing that degrades user experience and blocks the main thread.