LCP
Largest Contentful Paint
4.9s
Poor
Good: < 2.5s
Measures how long it takes for the main content to appear on screen
Fix JavaScript Forced Reflows
How to optimize tokyoportfolio.frontend.stg.vercel.app
Fix JavaScript Forced Reflows
High Impact+10 points estimated
Why It Matters
JavaScript is causing 149ms of forced reflows by reading layout properties after DOM changes, blocking the main thread.
How to Fix
Batch DOM reads and writes to avoid layout thrashing. Use React's useLayoutEffect sparingly and prefer useEffect. Implement virtual scrolling for large lists using libraries like react-window. Cache DOM measurements and avoid accessing offsetWidth/offsetHeight in loops.
0Needs Improvement
What This Score Means
A score of 76 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
187ms
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
This Next.js site has below-average performance with a score of 76/100. The biggest problem is render-blocking CSS files that are delaying your First Contentful Paint by 600ms, with one stylesheet containing 87% unused CSS rules that could save 18KB. Additionally, your Largest Contentful Paint is suffering at 4.9 seconds and Time to Interactive is extremely slow at 10.5 seconds, largely due to forced reflows in your JavaScript and inefficient resource loading. Eliminating unused CSS, optimizing JavaScript execution, and implementing better caching strategies could improve your Core Web Vitals significantly and provide a much better user experience.
Other Optimization Recommendations
Eliminate Render Blocking CSS
High Impact+12 points estimatedWhy It Matters:
CSS files are blocking initial render by 580ms, directly delaying FCP and potentially LCP.
How to Fix:
In your Next.js app, inline critical above-the-fold CSS using next/dynamic with ssr: false for non-critical components. Split CSS by route using Next.js automatic code splitting. Use next/head to preload CSS files or consider CSS-in-JS solutions like styled-components for better performance.
Remove Unused CSS Rules
Medium Impact+8 points estimatedWhy It Matters:
87% of your main CSS bundle (18KB) is unused, wasting bandwidth and parse time.
How to Fix:
Use PurgeCSS with Next.js to automatically remove unused styles during build. Configure Tailwind CSS purging properly in your tailwind.config.js. Implement CSS modules or styled-components to ensure only component-specific styles are loaded. Use Next.js built-in CSS optimization features.
Keep Your Site Fast After Optimization
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Related Performance Analyses
More Next.js Speed Tests
Next.js Performance Resources
Reduce Unused CSS and JavaScript
You're loading 287KB of unused JavaScript and 19KB of unused CSS, blocking rendering and slowing page load.
Fix Cumulative Layout Shift
Your CLS score of 0.806 is extremely poor (needs <0.1) with the footer element causing massive layout shifts.
Optimize Third-Party JavaScript
Google Analytics and Facebook Pixel scripts consume 213KB of unused JavaScript and cause 57ms of forced reflows.
Eliminate CSS Render Blocking
CSS files are blocking initial page render for 870ms and delaying First Contentful Paint by 850ms.