Performance
· 14 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.
419 ms
Largest Contentful Paint Largest Contentful Paint — how long until the largest visible element loads. Under 2.5s is good.
2.41 s
Total Blocking Time Total Blocking Time — total time the main thread was blocked, preventing user input. Under 200ms is good.
107 ms
Cumulative Layout Shift Cumulative Layout Shift — measures visual stability. How much the page layout shifts during loading. Under 0.1 is good.
0.017
Speed Index Speed Index — how quickly content is visually displayed during load. Under 3.4s is good.
826 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.
2.41 s
Page Load Progression
375 ms
750 ms
1.1 s 1.5 s 1.9 s 2.2 s 2.6 s 3.0 sDPage Weight BudgetAction2.2 MB transferred, 23 requestsFIX
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
Large JavaScript bundles delay interactivity. Split code by route or defer non-critical scripts.
JavaScript bundle is large — code-split routes and lazy-load off-screen components to defer.
Source: web.dev
FJS BundlesAction4 scripts, 572 KB unusedFIX
Downloaded but never executed on this page.
| Script | Size | Unused | Minified | Party |
|---|---|---|---|---|
| https://overheid.nl/sites/default/files/js/js_uOMZ6Shqc42Sf1wo7NmMYjjwm2inS8gWpjvbFOSqHho.js?scope=header&delta=0&language=nl&theme=koopoverheid_theme&include=eJxtytEJwCAMBcCFBEcSU18T0ZKSxILbd4D2-26o3vrABL2VEFzIPJXqTOMrHnuCV28oh_vfCDElgiVfzPCA5ajcz_0CnGop0Q | 603 KB | 496 KB (82%) | ✓ | 1st |
| https://overheid.nl/sites/default/files/js/js_RGZDxG-0U-PNstrwDRvFXIEZx7FI45u607ekWWKg7vk.js?scope=footer&delta=0&language=nl&theme=koopoverheid_theme&include=eJxtytEJwCAMBcCFBEcSU18T0ZKSxILbd4D2-26o3vrABL2VEFzIPJXqTOMrHnuCV28oh_vfCDElgiVfzPCA5ajcz_0CnGop0Q | 61 KB | 40 KB (66%) | ✓ | 1st |
| https://koop.piwik.pro/containers/042a8a3e-7692-4e18-8abf-c3034df672d0.js?use_secure_cookies | 81 KB | 36 KB (44%) | ✓ | 3rd |
| https://koop.piwik.pro/ppms.js | 26 KB | — | ✓ | 3rd |
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
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
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
DPage Weight InventoryAction23 resources · 2.2 MB · 572 KB savings availableFIX
~572.4 KiB of savings available
| # | Resource | Type | Size | Cache | Unused | 3rd party | Issues |
|---|---|---|---|---|---|---|---|
| — | — | ||||||
| 23 resources | 2.2 MiB | ||||||
BImage Optimization9 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
CGreen HostingActionWhether the site is served from green-energy infrastructureREVIEW
Green Hosting
No green hosting detected
A+Third-Party Impact5% third-party, 0 ms blockingPASS
A+Text CompressionAll text resources are compressedPASS
A+JS Execution Cost160ms total JS executionPASS
Main Thread Breakdown
| Script | Total | Scripting | Parse/Compile | Party |
|---|---|---|---|---|
| https://overheid.nl/sites/default/files/js/js_uOMZ6Shqc42Sf1wo7NmMYjjwm2inS8gWpjvbFOSqHho.js?scope=header&delta=0&language=nl&theme=koopoverheid_theme&include=eJxtytEJwCAMBcCFBEcSU18T0ZKSxILbd4D2-26o3vrABL2VEFzIPJXqTOMrHnuCV28oh_vfCDElgiVfzPCA5ajcz_0CnGop0Q | 160ms | 111ms | 43ms | 1st |
A+Font Loading2 fonts (143 KB)PASS
Web fonts
2
143 KB total
Render-blocking
0
of 2
Dominant font-display
swap
Most common across fonts
Font loading timeline
- Convert to woff2 for ~30% smaller file size
- 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 ~43 KB and ~86 ms
A+Resource CachingAll resources properly cachedPASS
A+Critical Rendering PathNo render-blocking resourcesPASS
A+Resource HintsNo optimization neededPASS
A+HTTP Cachingmax-age=31536000 (52 weeks)PASS
max-age=31536000, public
| Directive | Value | Meaning |
|---|---|---|
| max-age | 31536000 | Cache for 52 weeks |
| public | — | Any cache may store this response |