LCP
Largest Contentful Paint
5.9s
Poor
Good: < 2.5s
Measures how long it takes for the main content to appear on screen
Optimize JavaScript Execution Performance
How to optimize landing.dev.opencals.com
Optimize JavaScript Execution Performance
High Impact+15 points estimated
Why It Matters
7.6 seconds of JavaScript execution time creates 2.3 seconds of blocking time, preventing user interactions.
How to Fix
Split large JavaScript chunks using Next.js dynamic imports and code splitting. Move heavy computations to Web Workers or defer to after page load. Use React.memo and useMemo to prevent unnecessary re-renders in your components.
0Poor
What This Score Means
A score of 43 falls in the "Poor" 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
1277ms
Poor
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/React landing page has poor performance with a score of 43/100, indicating significant user experience issues. The biggest problem is excessive JavaScript that takes 7.6 seconds to execute, with 140 KB of unused code that could be removed entirely, which is severely delaying your Largest Contentful Paint (5.9 seconds) and making the page unresponsive for over 2 seconds. The site would benefit most from code splitting to reduce the initial JavaScript bundle size, removing unused code, and optimizing the build process to avoid unnecessary polyfills for modern browsers. These JavaScript optimizations alone could potentially improve your performance score by 30+ points and dramatically reduce loading times.
Other Optimization Recommendations
Remove Unused JavaScript Code
High Impact+18 points estimatedWhy It Matters:
140 KiB of unused JavaScript delays LCP by 950ms and blocks user interactions.
How to Fix:
Use Next.js bundle analyzer to identify unused code in chunks. Implement dynamic imports for heavy components that aren't immediately needed. Configure webpack tree-shaking to eliminate dead code from your main bundle.
Fix Forced Reflow Issues
Medium Impact+8 points estimatedWhy It Matters:
DOM queries after style changes cause 206ms of forced reflows, degrading rendering performance.
How to Fix:
Batch DOM reads before writes in your React components. Use CSS transforms instead of changing layout properties. Replace synchronous DOM measurements with ResizeObserver or IntersectionObserver APIs where possible.
Keep Your Site Fast After Optimization
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Related Performance Analyses
More Next.js Speed Tests
Next.js Performance Resources
Modernize JavaScript Build Target
Legacy JavaScript polyfills add 13 KiB and 150ms to LCP for features modern browsers support natively.
Remove Unused JavaScript Code
140 KiB of unused JavaScript delays LCP by 950ms and blocks user interactions.
Fix Forced Reflow Issues
DOM queries after style changes cause 206ms of forced reflows, degrading rendering performance.
Inline Critical CSS Bundle
Render-blocking CSS delays LCP and FCP by 100ms each, preventing critical content from displaying.