LCP
Largest Contentful Paint
3.8s
Needs Improvement
Good: < 2.5s
Measures how long it takes for the main content to appear on screen
Optimize Legacy JavaScript Polyfills
How to optimize koditt.nl
Optimize Legacy JavaScript Polyfills
Medium Impact+8 points estimated
Why It Matters
Modern browser features are being unnecessarily polyfilled, adding 14 KiB of redundant code that slows parsing.
How to Fix
Update your Next.js browserslist configuration to target modern browsers (>95% support). Remove polyfills for Array.prototype.at, Object.hasOwn, and other Baseline features. Use differential serving to send modern JS to capable browsers.
0Needs Improvement
What This Score Means
A score of 75 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
232ms
Needs Improvement
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 mediocre performance with a score of 75/100, but several critical issues are holding it back. The biggest problem is excessive unused JavaScript (453 KiB of wasted code) which is causing a slow Time to Interactive of 6.8 seconds and blocking the main thread for 6 seconds. The site is also experiencing forced reflows that create a sluggish First Input Delay of 230ms, making interactions feel unresponsive. Removing unused JavaScript from Google Tag Manager and other scripts, along with fixing the layout thrashing issues, could dramatically improve both loading speed and user interactivity.
Other Optimization Recommendations
Reduce Unused JavaScript Bundle Size
High Impact+15 points estimatedWhy It Matters:
Unused JavaScript is consuming 453 KiB and delaying LCP by 600ms while blocking main thread interactions.
How to Fix:
Implement code splitting in your Next.js app using dynamic imports for large components. Use next-bundle-analyzer to identify unused dependencies. Configure tree-shaking properly and consider lazy loading Google Analytics/Tag Manager scripts after user interaction.
Eliminate Forced Layout Reflows
High Impact+12 points estimatedWhy It Matters:
JavaScript is triggering 389ms of forced reflows, significantly impacting First Input Delay and user interactivity.
How to Fix:
Audit the JavaScript chunks causing reflows (0zut2zdu159pe.js and 03dhd84dz2389.js). Batch DOM reads and writes together. Use CSS transforms instead of changing layout properties. Consider using React's Concurrent features to break up long tasks.
Keep Your Site Fast After Optimization
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Related Performance Analyses
More Next.js Speed Tests
Next.js Performance Resources
Add Preconnect Headers for External Origins
Missing preconnect hints to CMS and Cookiebot domains waste 300ms each on connection setup.
Fix Cookie Dialog Element Render
Cookie dialog causes 5.2 second element render delay, making it the LCP element instead of actual content.
Add Preconnect to External Origins
Missing preconnect to cms.koditt.dev delays LCP by 323ms due to late connection establishment.
Eliminate Unused JavaScript Bundle
455 KiB of unused JavaScript delays LCP by 450ms and blocks main thread execution.