LCP
Largest Contentful Paint
17.9s
Poor
Good: < 2.5s
Measures how long it takes for the main content to appear on screen
Fix Critical JavaScript Performance Issues
How to optimize heijmansnieuwbouw.nl
Next.js SiteScore: 53/100Analyzed February 2026
Fix Critical JavaScript Performance Issues
High Impact+25 points estimated
Why It Matters
JavaScript execution takes 1.9 seconds and blocks main thread, causing the extremely poor LCP of 17.9s and high TBT of 680ms.
How to Fix
Remove unused JavaScript (324 KiB savings identified). Split large chunks like 6920-de8fc29eacd8dcbe.js using Next.js dynamic imports with React.lazy(). Defer Google Tag Manager and analytics scripts until after page load using Next.js Script component with strategy='afterInteractive'.
0Needs Improvement
What This Score Means
A score of 53 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
261ms
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 poor performance with a score of 53/100. The biggest problem is an extremely slow Largest Contentful Paint of 17.9 seconds, caused by render-blocking CSS files and inefficient resource loading that could be improved by 1.4 seconds. The site is also weighed down by 324 KiB of unused JavaScript from Google Tag Manager and other scripts, plus oversized images that could be compressed to save 470 KiB. Fixing the CSS blocking issues, removing unused code, and optimizing image compression could dramatically improve load times and boost the performance score by 30+ points.
Other Optimization Recommendations
Eliminate Render-Blocking CSS Resources
High Impact+18 points estimatedWhy It Matters:
CSS files block first paint for 1.37 seconds, preventing users from seeing content quickly.
How to Fix:
Use Next.js built-in CSS optimization by moving critical styles inline with styled-jsx or CSS-in-JS. Implement CSS code splitting by component level. Remove unused CSS rules (83% of CybotCookiebot styles are unused). Load non-critical CSS asynchronously using next/dynamic.
Optimize LCP Hero Image Loading
High Impact+15 points estimatedWhy It Matters:
The LCP image takes 2.3 seconds to load due to poor compression and causes most of the 17.9s LCP delay.
How to Fix:
Compress the hero image 'Rijwoningen in aanbouw' by 60KB using next/image with quality={75} instead of q=100. Add priority={true} to the LCP image. Implement resource hints by adding preconnect links to backend.heijmansnieuwbouw.nl in next/head.
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Related Performance Analyses
More Next.js Speed Tests
Next.js Performance Resources
Eliminate Duplicate JavaScript Modules
175 KiB of duplicated JavaScript from Nike Design System components is loaded multiple times across bundles.
Fix LCP Image Discovery
The LCP image is not discoverable in the initial HTML, causing a 4-second resource load delay.
Remove Unused JavaScript Code
460 KiB of unused JavaScript is blocking the main thread for 7.3 seconds and delaying LCP by 2.4 seconds.
Fix Page Redirects Chain
Multiple redirects add 1.53 seconds delay before the page even starts loading, directly impacting both FCP and LCP.
Frequently Asked Questions
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