Browsers will use heuristic caching, which can be unpredictable. Set explicit cache headers.
No Cache-Control header
Adding a Cache-Control header can significantly improve repeat-visit performance.
C
Image Optimization
Action
44 images, 0 KB saveable
REVIEW
44 images, 0 KB saveable
Warning::
!
https://www.bnnvara.nl/static/logo/bnnvaraRed.svg is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.bnnvara.nl/static/logo/bnnvaraWijZijnV... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
44images879 KB
0oversized-0 KB
8legacy format
2missing dimensionsCLS risk
Set explicit width and height to prevent CLS.
Why this matters
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.
Why this matters
Image without explicit width/height — browser can't reserve space; CLS jumps when image loads.
Source: web.dev / Core Web Vitals
B
HTTP/3 (QUIC)
HTTP/3 not advertised
REVIEW
HTTP/3 not advertised
Info::
i
HTTP/3 (QUIC) is not advertised
HTTP/3 isn't advertised via Alt-Svc and the worker didn't negotiate h3. HTTP/3 reduces handshake latency (1-RTT instead of 2-3 RTTs) and is more resilient on lossy connections. Most modern CDNs (Cloudflare, Fastly, AWS CloudFront, Google Cloud CDN) support HTTP/3 with a single config switch -- consider enabling for mobile-heavy workloads.
C
Compression Algorithm
Action
Main response served uncompressed
REVIEW
Main response served uncompressed
Info::
i
Main HTML response has no Content-Encoding (uncompressed)
The main HTML document is served without compression. The Text Compression section above lists the broader picture; for the main response specifically, even gzip would shave ~70-80% off most text payloads.
B
Main HTML Cache-Control
No Cache-Control header on main HTML response
REVIEW
No Cache-Control header on main HTML response
Info::
i
Main HTML response has no Cache-Control header
Without an explicit Cache-Control, browsers fall back to heuristic caching (~10% of Last-Modified age). Set `Cache-Control: no-cache` or `max-age=300` for HTML to control freshness explicitly -- prevents stale auth state and SPA shell drift.
B
Server-Timing Observability
No Server-Timing header found
REVIEW
No Server-Timing header found
Info::
i
No Server-Timing header found
Server-Timing exposes backend timing breakdowns to browser DevTools (e.g., `db: 45ms; render: 120ms; cache: 2ms`). Useful for diagnosing slow pages without backend log access. Most modern frameworks (Next.js, Cloudflare Workers, Fastly) emit it automatically; absence on a managed platform usually means telemetry headers are stripped at the edge.
B
JavaScript Blocking
2 JS blocking issue(s) detected
REVIEW
2 JS blocking issue(s) detected
Warning::
!
3 render-blocking <script src> tag(s) without async/defer
Each `<script src=...>` without `async`, `defer`, or `type="module"` blocks HTML parsing while the browser fetches and executes it. The block lasts the entire round-trip + execution time -- on slow networks this translates directly into LCP delay. Add `defer` (executes after parse, in source order) for scripts that interact with the DOM, or `async` (executes whenever ready) for analytics / independent scripts. Module scripts (`type="module"`) are deferred by default.
Warning::
!
Total JS execution time is 7.0 s -- over the 3.5s budget
Total JavaScript execution (parse + compile + run) across all scripts exceeds 3.5 seconds. On low-end devices that becomes 7-15+ seconds and shows up directly in TBT and INP. Reduce by: tree-shaking unused dependencies, code-splitting (dynamic `import()`), removing or deferring third-party tracking, and replacing heavy frameworks where they're not needed.
C
Green Hosting
Action
Whether the site is served from green-energy infrastructure
REVIEW
Green Hosting
No green hosting detected
A+
Text Compression
All text resources are compressed
PASS
All text resources are compressed
Info::
✓
All text resources are compressed
All text resources are properly compressed.
A+
Font Loading
10 fonts (428 KB)
PASS
10 fonts (428 KB)
Info::
i
10 font(s) use font-display: swap (FOUT risk but functional)
Web fonts
10
428 KB total
Render-blocking
0
of 10
Dominant font-display
swap
Most common across fonts
Font loading timeline
TransferFOIT (block)FOUT (swap)
1e5e3bc8b6da7e03-s.p.woffwoffswap
Size28 KB
Load time187 ms
Start299 ms
RiskFOUT — text flashes from fallback to web font
Convert to woff2 for ~30% smaller file size
2bf0a01107660069-s.p.woffwoffswap
Size30 KB
Load time223 ms
Start299 ms
RiskFOUT — text flashes from fallback to web font
Convert to woff2 for ~30% smaller file size
d15acd911aceaf2d-s.p.woffwoffswap
Size28 KB
Load time234 ms
Start299 ms
RiskFOUT — text flashes from fallback to web font
Convert to woff2 for ~30% smaller file size
eb12272399e67777-s.p.woffwoffswap
Size29 KB
Load time210 ms
Start300 ms
RiskFOUT — text flashes from fallback to web font
Convert to woff2 for ~30% smaller file size
55645d5ca49ac509-s.p.woffwoffswap
Size29 KB
Load time240 ms
Start300 ms
RiskFOUT — text flashes from fallback to web font
Convert to woff2 for ~30% smaller file size
1d38352909027b4b-s.p.woffwoffswap
Size28 KB
Load time217 ms
Start300 ms
RiskFOUT — text flashes from fallback to web font
Convert to woff2 for ~30% smaller file size
Haffer-Bold.woffwoffswap
Size77 KB
Load time66 ms
Start3.1 s
RiskFOUT — text flashes from fallback to web font
Convert to woff2 for ~30% smaller file size
Haffer-SemiBold.woffwoffswap
Size77 KB
Load time96 ms
Start3.1 s
RiskFOUT — text flashes from fallback to web font
Convert to woff2 for ~30% smaller file size
Haffer-Regular.woffwoffswap
Size76 KB
Load time96 ms
Start3.1 s
RiskFOUT — text flashes from fallback to web font
Convert to woff2 for ~30% smaller file size
Haffer-Medium.woffwoffswap
Size26 KB
Load time92 ms
Start3.1 s
RiskFOUT — text flashes from fallback to web font
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 ~128 KB and ~256 ms
A+
Resource Caching
All resources properly cached
PASS
All resources properly cached
Info::
✓
No caching issues found
All static resources have appropriate caching headers.
A+
Critical Rendering Path
No render-blocking resources
PASS
No render-blocking resources
Info::
✓
No render-blocking resources detected
A+
Resource Hints
10 hints, 0 missing preconnects
PASS
10 hints, 0 missing preconnects
Info::
✓
Page uses 10 resource hint(s)
Current Resource Hints
preconnect—
preload
8
dns-prefetch—
prefetch
2
10 resource hints configured
A+
LCP Image Preload
LCP preload audit not available
PASS
LCP preload audit not available
Info::
✓
LCP image preload audit not available for this scan
A+
Server Response Intelligence
1 server-response signal(s) detected
PASS
1 server-response signal(s) detected
Info::
i
No `ETag` or `Last-Modified` -- conditional GET not supported
Without either header, browsers can't issue conditional GETs and refresh always re-downloads the full response body even when nothing changed. Add `ETag: "<hash>"` (or `Last-Modified: <date>`) on cacheable responses; the server returns 304 Not Modified when the client's cached copy is still valid, saving bandwidth.
A+
Render-Blocking Resources
No render-blocking resources detected
PASS
No render-blocking resources detected
Info::
✓
No render-blocking resources detected in <head>
A+
Third-Party Resources
No third-party resources detected
PASS
No third-party resources detected
A+
CSS Performance Depth
No CSS performance depth issues detected
PASS
No CSS performance depth issues detected
Info::
✓
No CSS performance depth issues detected
Network Waterfall
165 requests over 3245ms
INFO
HTML JavaScript CSS Images Fonts XHR/Fetch Other
Third-Party Script Cost
Per-script blocking time, transfer cost, and cache headers
INFO
87%of JavaScript execution is third-party
First-party Third-party6159ms · 1323KB · €67/mo
Script
Category
Execution
Transfer
Unused
Monthly Cost
Verdict
static.bnnvara.nl
static.bnnvara.nl
Other
2211ms
67 KB
35%
€24/mo
Costly
static.bnnvara.nl
static.bnnvara.nl
Other
1061ms
172 KB
40%
€12/mo
Costly
static.bnnvara.nl
static.bnnvara.nl
Other
572ms
2 KB
—
€6/mo
Costly
Google Tag Manager
www.googletagmanager.com
Tag Manager
571ms
185 KB
34%
€6/mo
Costly
www.bnnvara.nl
www.bnnvara.nl
Other
515ms
55 KB
—
€6/mo
Costly
Google Tag Manager
www.googletagmanager.com
Tag Manager
408ms
179 KB
39%
€4/mo
Costly
Hotjar
script.hotjar.com
Session Replay
184ms
57 KB
66%
€2/mo
Optional
static.bnnvara.nl
static.bnnvara.nl
Other
113ms
39 KB
—
€1/mo
Optional
npotag.npo-data.nl
npotag.npo-data.nl
Other
94ms
83 KB
45%
€1/mo
Optional
Google Tag Manager
www.googletagmanager.com
Tag Manager
88ms
185 KB
63%
€1/mo
Optional
vibe.bnnvara.nl
vibe.bnnvara.nl
Other
81ms
22 KB
98%
€1/mo
Optional
ccm.npo.nl
ccm.npo.nl
Other
76ms
8 KB
—
€1/mo
Optional
cdn.optoutadvertising.com
cdn.optoutadvertising.com
Other
72ms
51 KB
65%
€1/mo
Optional
static.bnnvara.nl
static.bnnvara.nl
Other
62ms
16 KB
—
€1/mo
Optional
static.bnnvara.nl
static.bnnvara.nl
Other
51ms
201 KB
67%
€1/mo
Optional
static.bnnvara.nl
Other
Costly
Execution2211ms
Transfer67 KB
Unused35%
Monthly Cost€24/mo
static.bnnvara.nl
Other
Costly
Execution1061ms
Transfer172 KB
Unused40%
Monthly Cost€12/mo
static.bnnvara.nl
Other
Costly
Execution572ms
Transfer2 KB
Monthly Cost€6/mo
Google Tag Manager
Tag Manager
Costly
Execution571ms
Transfer185 KB
Unused34%
Monthly Cost€6/mo
www.bnnvara.nl
Other
Costly
Execution515ms
Transfer55 KB
Monthly Cost€6/mo
Google Tag Manager
Tag Manager
Costly
Execution408ms
Transfer179 KB
Unused39%
Monthly Cost€4/mo
Hotjar
Session Replay
Optional
Execution184ms
Transfer57 KB
Unused66%
Monthly Cost€2/mo
static.bnnvara.nl
Other
Optional
Execution113ms
Transfer39 KB
Monthly Cost€1/mo
npotag.npo-data.nl
Other
Optional
Execution94ms
Transfer83 KB
Unused45%
Monthly Cost€1/mo
Google Tag Manager
Tag Manager
Optional
Execution88ms
Transfer185 KB
Unused63%
Monthly Cost€1/mo
vibe.bnnvara.nl
Other
Optional
Execution81ms
Transfer22 KB
Unused98%
Monthly Cost€1/mo
ccm.npo.nl
Other
Optional
Execution76ms
Transfer8 KB
Monthly Cost€1/mo
cdn.optoutadvertising.com
Other
Optional
Execution72ms
Transfer51 KB
Unused65%
Monthly Cost€1/mo
static.bnnvara.nl
Other
Optional
Execution62ms
Transfer16 KB
Monthly Cost€1/mo
static.bnnvara.nl
Other
Optional
Execution51ms
Transfer201 KB
Unused67%
Monthly Cost€1/mo
These scripts may cost more than they're worth
static.bnnvara.nl adds 2211ms and costs ~€24/month
static.bnnvara.nl adds 1061ms and costs ~€12/month
static.bnnvara.nl adds 572ms and costs ~€6/month
Google Tag Manager adds 571ms and costs ~€6/month
www.bnnvara.nl adds 515ms and costs ~€6/month
Google Tag Manager adds 408ms and costs ~€4/month
87% of JavaScript execution time is spent on third-party scripts. Consider auditing which scripts are essential.
Why this matters
When third-party JS execution time exceeds your own, performance gains from frontend work are capped by code you don't own.
Learn more ▾▴
Every millisecond of third-party JS competes with your own for main-thread time. If their share is bigger than yours, optimization on your code base barely moves the needle. Audit, defer, or remove third-parties before further frontend optimization. Use Lighthouse's third-party audit to identify the worst offenders.
Source: web.dev
static.bnnvara.nl takes 2211ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
Why this matters
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
static.bnnvara.nl takes 1061ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
Why this matters
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
static.bnnvara.nl takes 572ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
Why this matters
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
Google Tag Manager takes 571ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
Why this matters
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
www.bnnvara.nl takes 515ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
Why this matters
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
Google Tag Manager takes 408ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
Why this matters
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
66% of Hotjar's code is unused. The script may be loading features you don't use.
Why this matters
Bundle has high unused-code ratio — tree-shaking and route-splitting recover the wasted bytes.
Source: web.dev
63% of Google Tag Manager's code is unused. The script may be loading features you don't use.
Why this matters
Bundle has high unused-code ratio — tree-shaking and route-splitting recover the wasted bytes.
Source: web.dev
98% of vibe.bnnvara.nl's code is unused. The script may be loading features you don't use.
Why this matters
Bundle has high unused-code ratio — tree-shaking and route-splitting recover the wasted bytes.
Source: web.dev
65% of cdn.optoutadvertising.com's code is unused. The script may be loading features you don't use.
Why this matters
Bundle has high unused-code ratio — tree-shaking and route-splitting recover the wasted bytes.
Source: web.dev
67% of static.bnnvara.nl's code is unused. The script may be loading features you don't use.
Why this matters
Bundle has high unused-code ratio — tree-shaking and route-splitting recover the wasted bytes.