Performance
· 23 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.Performance-focused optimization plan with CWV assessment, top offenders, and time estimates
First Contentful Paint First Contentful Paint — how long until the browser renders the first piece of content. Under 1.8s is good.
610 ms
Largest Contentful Paint Largest Contentful Paint — how long until the largest visible element loads. Under 2.5s is good.
1.48 s
Total Blocking Time Total Blocking Time — total time the main thread was blocked, preventing user input. Under 200ms is good.
0 ms
Cumulative Layout Shift Cumulative Layout Shift — measures visual stability. How much the page layout shifts during loading. Under 0.1 is good.
0.002
Speed Index Speed Index — how quickly content is visually displayed during load. Under 3.4s is good.
812 ms
Time to Interactive Time to Interactive — how long until the page is fully interactive and responds to user input. Under 3.8s is good.
1.49 s
Page Load Progression
BPage Weight Budget1.5 MB transferred, 82 requestsREVIEW
Convert images to WebP/AVIF and resize to display dimensions to reduce transfer size.
Image bandwidth is high — modern formats (WebP/AVIF) and resizing typically cut it 50%+.
Source: web.dev
CImage OptimizationAction8 images, 0 KB saveableREVIEW
Set explicit width and height to prevent CLS.
Image without explicit width/height — browser can't reserve space; CLS jumps when image loads.
Source: web.dev / Core Web Vitals
Set explicit width and height to prevent CLS.
Image without explicit width/height — browser can't reserve space; CLS jumps when image loads.
Source: web.dev / Core Web Vitals
Set explicit width and height to prevent CLS.
Image without explicit width/height — browser can't reserve space; CLS jumps when image loads.
Source: web.dev / Core Web Vitals
Set explicit width and height to prevent CLS.
Image without explicit width/height — browser can't reserve space; CLS jumps when image loads.
Source: web.dev / Core Web Vitals
Set explicit width and height to prevent CLS.
Image without explicit width/height — browser can't reserve space; CLS jumps when image loads.
Source: web.dev / Core Web Vitals
Set explicit width and height to prevent CLS.
Image without explicit width/height — browser can't reserve space; CLS jumps when image loads.
Source: web.dev / Core Web Vitals
Set explicit width and height to prevent CLS.
Image without explicit width/height — browser can't reserve space; CLS jumps when image loads.
Source: web.dev / Core Web Vitals
BHTTP/3 (QUIC)HTTP/3 not advertisedREVIEW
BDocument CompressionDocument response uses gzip; brotli would be ~20% smallerREVIEW
BServer-Timing ObservabilityNo Server-Timing header foundREVIEW
CPage Weight InventoryAction82 resources · 1.5 MB · 38 KB savings availableREVIEW
~37.7 KiB of savings available
| # | Resource | Type | Size | Cache | Unused | 3rd party | Issues |
|---|---|---|---|---|---|---|---|
| — | — | ||||||
| 82 resources | 1.5 MiB | ||||||
BHTTP Cachingno-cacheREVIEW
no-cache
| Directive | Value | Meaning |
|---|---|---|
| no-cache | — | Cache but always revalidate first |
A+Third-Party Impact13% third-party, 0 ms blockingPASS
A+Text CompressionAll text resources are compressedPASS
A+JS Execution Cost171ms total JS executionPASS
Main Thread Breakdown
| Script | Total | Scripting | Parse/Compile | Party |
|---|---|---|---|---|
| https://www.nieuwegein.nl/ | 89ms | 1ms | 0ms | 1st |
| Unattributable | 81ms | 2ms | 0ms | 1st |
A+Font Loading5 fonts (142 KB)PASS
Web fonts
5
142 KB total
Render-blocking
0
of 5
Dominant font-display
swap
Most common across fonts
Font loading timeline
- Convert to woff2 for ~30% smaller file size
Optimization checklist
- Preload critical fonts (priority=high)
- Use woff2 format for all fonts
- Set font-display to swap, optional, or fallback
- Subset large fonts (≤100 KB each)
Fixing the unchecked items could save ~11 KB and ~22 ms
A+JS Bundles16 scripts, 38 KB unusedPASS
Downloaded but never executed on this page.
| Script | Size | Unused | Minified | Party |
|---|---|---|---|---|
| https://nieuwegein.containers.piwik.pro/8c3a49ae-a53a-483e-88b5-83285fa6def9.js | 71 KB | 38 KB (54%) | ✓ | 3rd |
| https://www.nieuwegein.nl/_assets/317130fbcbb12622b6e28e3bfff3cb16/Js/OpenGemeentenSite-FragmentScroll.min.js?1794362666 | 1 KB | — | ✓ | 1st |
| https://www.nieuwegein.nl/_assets/317130fbcbb12622b6e28e3bfff3cb16/Js/OpenGemeentenSite-Viewport.min.js?1794362666 | 1 KB | — | ✓ | 1st |
| https://cdn-eu.readspeaker.com/script/4864/webReader/webReader.js?pids=wr | 28 KB | — | ✓ | 3rd |
| https://www.nieuwegein.nl/typo3temp/assets/js/0f851906d0fb8bbe408c0ec9ef59dfcc.js?1794362979 | 1 KB | — | ✓ | 1st |
| https://www.nieuwegein.nl/typo3temp/assets/js/b2a489e189e35731ae576f29d4e92018.js?1794362979 | 1 KB | — | ✓ | 1st |
| https://www.nieuwegein.nl/_assets/6c3bf359f8df9d9222347f37e2814501/JavaScript/OpenGemeentenSiteSearch-Suggest.min.js?1794362666 | 2 KB | — | ✓ | 1st |
| https://nieuwegein.containers.piwik.pro/8c3a49ae-a53a-483e-88b5-83285fa6def9.sync.js | 0 KB | — | ✓ | 3rd |
| https://www.nieuwegein.nl/_assets/317130fbcbb12622b6e28e3bfff3cb16/Js/OpenGemeentenSite-Media.min.js?1794362666 | 2 KB | — | ✓ | 1st |
| https://www.nieuwegein.nl/_assets/317130fbcbb12622b6e28e3bfff3cb16/Js/OpenGemeentenSite-Focusable.min.js?1794362666 | 0 KB | — | ✓ | 1st |
Consider code splitting or tree shaking to reduce unused code.
This bundle has high unused code — code-split or tree-shake to ship only what executes.
Source: web.dev / Lighthouse coverage
A+Resource CachingAll resources properly cachedPASS
A+Critical Rendering PathNo render-blocking resourcesPASS
A+Resource HintsNo optimization neededPASS
AAsset Compression1 of 1 asset host still on gzipPASS
A+LCP Image PreloadLCP preload audit not availablePASS
A+Main HTML Cache-ControlMain HTML uses no-cache -- safe revalidate-on-request policyPASS
A+Server Response Intelligence2 server-response signal(s) detectedPASS
A+Green HostingWhether the site is served from green-energy infrastructurePASS
Green Hosting
This site is hosted on green energy infrastructure
Provider: Leaseweb Global BV
Network Waterfall82 requests over 965msINFO
Real-User Performance (CrUX)Field metrics from the Chrome User Experience ReportINFO
Chrome User Experience (CrUX)
Real-user metrics from the Chrome UX Report (2026-10-14 — 2026-11-10)
LCP (p75)
1015 ms
90% good
INP (p75)
63 ms
99% good
CLS (p75)
0.000
100% good
FCP (p75)
1029 ms
TTFB (p75)
376 ms
Image Optimization8 images, 558 KB total, 0 KB wastedINFO
Image Optimization Audit
Total Images
8
Total Size
558 KB