Largest Contentful Paint
Good: < 2.5s
Measures how long it takes for the main content to appear on screen
How to optimize accept.nioz.nl
478KB of unused JavaScript is consuming network bandwidth and causing 2.4s of main thread blocking time.
Implement code splitting to load only necessary JavaScript per page. Remove unused citation and bibliography libraries (citeproc, bibtex plugins) if not needed. Use dynamic imports for components like lottie animations that aren't immediately required.
A score of 54 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.
Largest Contentful Paint
Good: < 2.5s
Measures how long it takes for the main content to appear on screen
Interaction to Next Paint
Good: < 200ms
Measures how quickly the page responds to user interactions
Cumulative Layout Shift
Good: < 0.1
Measures visual stability - how much content shifts during page load
This website has poor performance with a score of 54/100, indicating significant user experience issues. The biggest problem is extremely slow page loading, with the Largest Contentful Paint taking 13.9 seconds and First Contentful Paint at 5.7 seconds - both far exceeding acceptable standards. The primary culprits are massive amounts of unused CSS (93 KiB) and JavaScript (478 KiB) that are blocking the initial page render, plus inefficient caching policies that force users to re-download large files on every visit. Removing unused code, implementing proper caching headers, and optimizing the oversized images could easily improve the performance score by 30+ points and dramatically reduce loading times from nearly 14 seconds to under 3 seconds.
Why It Matters:
CSS files are blocking the initial page render, delaying both FCP by 5.7s and LCP by 13.9s with 450ms potential savings.
How to Fix:
Inline critical above-the-fold CSS directly in the HTML head. Split the large CSS bundle and defer non-critical styles using media='print' onload technique. Remove unused CSS rules which account for 87% of the main stylesheet (94KB savings).
Why It Matters:
Images lack explicit dimensions causing layout shifts and are oversized by 509KB, potentially affecting user experience.
How to Fix:
Add explicit width and height attributes to all img elements to prevent CLS. Convert the main carousel image from PNG to WebP format for 314KB savings. Implement responsive images with proper srcset attributes to serve appropriately sized images for different screen sizes.
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More Generic Speed Tests
Major layout shifts (CLS: 0.5) are caused by image carousel animations and unsized elements affecting user experience.
Critical JavaScript files are blocking page render for 1,370ms, severely delaying First Contentful Paint.
Images are causing 900ms LCP delay and consuming 498 KiB of unnecessary bandwidth with poor compression and oversized dimensions.
Blog images are oversized PNGs that could be 583KB smaller using modern formats, directly impacting LCP performance.