Consider code splitting or tree shaking to reduce unused code.
Why this matters
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.
Why this matters
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.
Why this matters
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.
Why this matters
This bundle has high unused code — code-split or tree-shake to ship only what executes.
Source: web.dev / Lighthouse coverage
B
Compression Algorithm
Main response uses gzip; brotli would be ~20% smaller
REVIEW
Main response uses gzip; brotli would be ~20% smaller
Info::
i
Main HTML response uses gzip (brotli would be ~20% smaller)
All current browsers support brotli. Most CDNs (Cloudflare, Fastly, AWS CloudFront, Vercel, Netlify) can switch from gzip to brotli with a single config flag. Origin servers (nginx, Apache) need a brotli module compiled in -- nginx-brotli or Apache mod_brotli.
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.
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+
JS Execution Cost
430ms total JS execution
PASS
430ms total JS execution
Info::
i
https://www.coloriet.nl/: 184ms CPU time
Info::
i
https://cdn.prod.website-files.com/69dccb80bcda8c9...: 125ms CPU time
15 font(s) use font-display: swap (FOUT risk but functional)
Web fonts
15
397 KB total
Render-blocking
0
of 15
Dominant font-display
swap
Most common across fonts
Font loading timeline
TransferFOIT (block)FOUT (swap)
lwoff2swap
Size61 KB
Load time12 ms
Start261 ms
RiskFOUT — text flashes from fallback to web font
lwoff2swap
Size60 KB
Load time12 ms
Start261 ms
RiskFOUT — text flashes from fallback to web font
S6u8w4BMUTPHh30AXC-qNiX...woff2swap
Size13 KB
Load time36 ms
Start403 ms
RiskFOUT — text flashes from fallback to web font
S6u-w4BMUTPHjxsIPx-oPCL...woff2swap
Size14 KB
Load time47 ms
Start403 ms
RiskFOUT — text flashes from fallback to web font
S6u9w4BMUTPHh7USSwiPGQ3...woff2swap
Size14 KB
Load time40 ms
Start404 ms
RiskFOUT — text flashes from fallback to web font
S6u_w4BMUTPHjxsI9w2_Gwf...woff2swap
Size14 KB
Load time49 ms
Start411 ms
RiskFOUT — text flashes from fallback to web font
S6uyw4BMUTPHjx4wXiWtFCc...woff2swap
Size14 KB
Load time55 ms
Start412 ms
RiskFOUT — text flashes from fallback to web font
S6u8w4BMUTPHjxsAXC-qNiX...woff2swap
Size15 KB
Load time67 ms
Start412 ms
RiskFOUT — text flashes from fallback to web font
S6u9w4BMUTPHh6UVSwiPGQ3...woff2swap
Size14 KB
Load time71 ms
Start412 ms
RiskFOUT — text flashes from fallback to web font
S6u_w4BMUTPHjxsI5wq_Gwf...woff2swap
Size15 KB
Load time77 ms
Start413 ms
RiskFOUT — text flashes from fallback to web font
S6u9w4BMUTPHh50XSwiPGQ3...woff2swap
Size13 KB
Load time73 ms
Start413 ms
RiskFOUT — text flashes from fallback to web font
S6u_w4BMUTPHjxsI3wi_Gwf...woff2swap
Size14 KB
Load time75 ms
Start413 ms
RiskFOUT — text flashes from fallback to web font
lwoff2swap
Size60 KB
Load time16 ms
Start513 ms
RiskFOUT — text flashes from fallback to web font
lwoff2swap
Size38 KB
Load time15 ms
Start513 ms
RiskFOUT — text flashes from fallback to web font
lwoff2swap
Size38 KB
Load time18 ms
Start515 ms
RiskFOUT — text flashes from fallback to web font
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)
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
No optimization needed
PASS
No optimization needed
Info::
✓
No resource hint issues
A+
HTTP/3 (QUIC)
HTTP/3 advertised via Alt-Svc
PASS
HTTP/3 advertised via Alt-Svc
Info::
✓
HTTP/3 (QUIC) is supported
First-load mobile users on cellular networks see meaningful latency improvements with HTTP/3. The QUIC transport collapses TLS + TCP handshakes into one and recovers faster from packet loss.
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
2 server-response signal(s) detected
PASS
2 server-response signal(s) detected
Info::
✓
`Vary` header declared: accept-encoding
The page declares a `Vary` header, telling downstream caches which request headers the response varies on. Critical for content-negotiated responses (compression, language, cookies, device class).
Info::
✓
`Last-Modified` present -- timestamp-based conditional GET supported
Consider also setting `ETag` for stronger revalidation -- ETags are content hashes that don't suffer from clock-skew or DST issues. Last-Modified alone is functional for conditional GETs and not a bug.
Network Waterfall
80 requests over 804ms
INFO
HTML JavaScript CSS Images Fonts XHR/Fetch Other
Third-Party Script Cost
Per-script blocking time, transfer cost, and cache headers