Fix Layout Shift Issues

How to optimize en.saif.sjtu.edu.cn

Generic SiteScore: 56/100Analyzed June 2026Re-analyze this site

Fix Layout Shift Issues

High Impact+15 points estimated

Why It Matters

Unsized media elements are causing 0.117 CLS score from images and videos loading without dimensions.

How to Fix

Add explicit width and height attributes to all img and video elements, especially the banner video and carousel images. Use CSS aspect-ratio or padding-bottom technique to reserve space before content loads. Preload the banner video poster image to prevent layout jumps.

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

LCP

Largest Contentful Paint

37.3s
Poor

Good: < 2.5s

Measures how long it takes for the main content to appear on screen

INP

Interaction to Next Paint

30ms
Good

Good: < 200ms

Measures how quickly the page responds to user interactions

CLS

Cumulative Layout Shift

0.12
Needs Improvement

Good: < 0.1

Measures visual stability - how much content shifts during page load

AI Performance Analysis

This website has poor performance with a score of 56/100, primarily due to extremely slow loading times. The biggest problem is the Largest Contentful Paint taking 37.3 seconds, caused by a massive 6.2-second resource load delay and oversized images that need optimization. The site is loading a 25MB payload including duplicate video files and uncompressed images, while also suffering from render-blocking CSS and JavaScript files that delay initial page rendering by 3.5 seconds. Optimizing images (which could save 8.6MB), implementing proper caching, and minifying JavaScript/CSS could dramatically improve performance and reduce the excessive load times that are severely impacting user experience.

Other Optimization Recommendations

Optimize Critical Image Delivery

High Impact+25 points estimated

Why It Matters:

Images are causing 19.2 seconds of LCP delay and using oversized files that are 8.6MB larger than needed.

How to Fix:

Convert all banner images to WebP format for 65% size reduction. Implement responsive images with proper srcset attributes matching display dimensions (720x343 instead of 2560x1219). Add fetchpriority='high' to the main banner image and ensure it's discoverable in initial HTML without JavaScript.

Eliminate Render Blocking Resources

High Impact+12 points estimated

Why It Matters:

Font and CSS files are blocking first paint for 3.5 seconds, delaying all content visibility.

How to Fix:

Add preconnect link for cdn.campuswit.com in HTML head. Use font-display: swap for custom fonts to show fallback text immediately. Inline critical CSS for above-the-fold content and defer non-critical stylesheets with media='print' onload technique.

Keep Your Site Fast After Optimization

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