Browsers will use heuristic caching, which can be unpredictable. Set explicit cache headers.
Info::
✓
Last-Modified header present
No Cache-Control header
Adding a Cache-Control header can significantly improve repeat-visit performance.
C
Image Optimization
Action
47 images, 0 KB saveable
REVIEW
47 images, 0 KB saveable
Warning::
!
https://cdnstoreapp.blob.core.windows.net/image-co... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://cdnstoreapp.blob.core.windows.net/image-co... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://cdnstoreapp.blob.core.windows.net/image-co... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://cdnstoreapp.blob.core.windows.net/image-co... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://cdnstoreapp.blob.core.windows.net/image-co... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://cdnstoreapp.blob.core.windows.net/image-co... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://cdnstorevoestalpine.blob.core.windows.net/... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://cdnstoreapp.blob.core.windows.net/image-co... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
47images43.7 MB
0oversized-0 KB
31legacy format
8missing 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
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
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
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.
B
Document Compression
Document response uses gzip; brotli would be ~20% smaller
REVIEW
Document 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.
B
JavaScript Blocking
2 JS blocking issue(s) detected
REVIEW
2 JS blocking issue(s) detected
Warning::
!
5 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 6.2 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 (172 KB)
PASS
10 fonts (172 KB)
Info::
i
10 font(s) use font-display: swap (FOUT risk but functional)
Web fonts
10
172 KB total
Render-blocking
0
of 10
Dominant font-display
swap
Most common across fonts
Font loading timeline
TransferFOIT (block)FOUT (swap)
voestalpine-Ultralight-...woffswap
Size21 KB
Load time14 ms
Start38 ms
RiskFOUT — text flashes from fallback to web font
Convert to woff2 for ~30% smaller file size
voestalpine-Light-WebS....woffswap
Size21 KB
Load time22 ms
Start41 ms
RiskFOUT — text flashes from fallback to web font
Convert to woff2 for ~30% smaller file size
voestalpine-Regular-Web...woffswap
Size22 KB
Load time22 ms
Start41 ms
RiskFOUT — text flashes from fallback to web font
Convert to woff2 for ~30% smaller file size
voestalpine-Medium-WebS...woffswap
Size22 KB
Load time25 ms
Start41 ms
RiskFOUT — text flashes from fallback to web font
Convert to woff2 for ~30% smaller file size
Glyphicons%20Voest.woffwoffswap
Size15 KB
Load time22 ms
Start41 ms
RiskFOUT — text flashes from fallback to web font
Convert to woff2 for ~30% smaller file size
font-woff2;charset=utf-...woff2swap
Size11 KB
Load time50 ms
Start2.3 s
RiskFOUT — text flashes from fallback to web font
6xK3dSBYKcSV-LCoeQqfX1R...woff2swap
Size15 KB
Load time8 ms
Start2.3 s
RiskFOUT — text flashes from fallback to web font
6xK1dSBYKcSV-LCoeQqfX1R...woff2swap
Size15 KB
Load time9 ms
Start2.4 s
RiskFOUT — text flashes from fallback to web font
6xKydSBYKcSV-LCoeQqfX1R...woff2swap
Size15 KB
Load time3 ms
Start2.8 s
RiskFOUT — text flashes from fallback to web font
6xKydSBYKcSV-LCoeQqfX1R...woff2swap
Size15 KB
Load time5 ms
Start2.8 s
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)
Fixing the unchecked items could save ~30 KB and ~60 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
3
preload
7
dns-prefetch—
prefetch—
10 resource hints configured
A+
Asset Compression
All 1 asset host use brotli
PASS
All 1 asset host use brotli
Info::
✓
www.googletagmanager.com serves assets with brotli (assets: 4)
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.
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
120 requests over 3796ms
INFO
HTML JavaScript CSS Images Fonts XHR/Fetch Other
Third-Party Script Cost
Per-script blocking time, transfer cost, and cache headers
INFO
47%of JavaScript execution is third-party
First-party Third-party2920ms · 1087KB · €32/mo
Script
Category
Execution
Transfer
Unused
Monthly Cost
Verdict
privacy-proxy.usercentrics.eu
privacy-proxy.usercentrics.eu
Other
610ms
30 KB
—
€7/mo
Costly
eu.acsbapp.com
eu.acsbapp.com
Other
544ms
241 KB
51%
€6/mo
Costly
app.usercentrics.eu
app.usercentrics.eu
Other
371ms
121 KB
45%
€4/mo
Costly
Google Tag Manager
www.googletagmanager.com
Tag Manager
361ms
166 KB
41%
€4/mo
Costly
Google Tag Manager
www.googletagmanager.com
Tag Manager
294ms
172 KB
49%
€3/mo
Costly
Google Tag Manager
www.googletagmanager.com
Tag Manager
238ms
148 KB
48%
€3/mo
Costly
usercentrics.voestalpine.com
usercentrics.voestalpine.com
Other
235ms
1 KB
—
€3/mo
Costly
Google Tag Manager
www.googletagmanager.com
Tag Manager
204ms
152 KB
44%
€2/mo
Costly
content.jwplatform.com
content.jwplatform.com
Other
63ms
55 KB
75%
€1/mo
Optional
privacy-proxy.usercentrics.eu
Other
Costly
Execution610ms
Transfer30 KB
Monthly Cost€7/mo
eu.acsbapp.com
Other
Costly
Execution544ms
Transfer241 KB
Unused51%
Monthly Cost€6/mo
app.usercentrics.eu
Other
Costly
Execution371ms
Transfer121 KB
Unused45%
Monthly Cost€4/mo
Google Tag Manager
Tag Manager
Costly
Execution361ms
Transfer166 KB
Unused41%
Monthly Cost€4/mo
Google Tag Manager
Tag Manager
Costly
Execution294ms
Transfer172 KB
Unused49%
Monthly Cost€3/mo
Google Tag Manager
Tag Manager
Costly
Execution238ms
Transfer148 KB
Unused48%
Monthly Cost€3/mo
usercentrics.voestalpine.com
Other
Costly
Execution235ms
Transfer1 KB
Monthly Cost€3/mo
Google Tag Manager
Tag Manager
Costly
Execution204ms
Transfer152 KB
Unused44%
Monthly Cost€2/mo
content.jwplatform.com
Other
Optional
Execution63ms
Transfer55 KB
Unused75%
Monthly Cost€1/mo
These scripts may cost more than they're worth
privacy-proxy.usercentrics.eu adds 610ms and costs ~€7/month
eu.acsbapp.com adds 544ms and costs ~€6/month
app.usercentrics.eu adds 371ms and costs ~€4/month
Google Tag Manager adds 361ms and costs ~€4/month
Google Tag Manager adds 294ms and costs ~€3/month
Google Tag Manager adds 238ms and costs ~€3/month
usercentrics.voestalpine.com adds 235ms and costs ~€3/month
Google Tag Manager adds 204ms and costs ~€2/month
47% of JavaScript execution time comes from third-party scripts.
Why this matters
Third-party scripts (analytics, ads, social, A/B testing) often dominate execution time — every one is a perf-and-privacy tax.
Learn more ▾▴
Each third-party script is a black box: you don't control when it loads, what it executes, or how much it grows. They often account for a major share of total blocking time on average sites (HTTP Archive's Web Almanac documents the trend). Audit which ones you actually need, defer the rest, and use facade patterns (lite-youtube, lite-vimeo) for embedded media.
Source: web.dev / HTTP Archive Web Almanac
privacy-proxy.usercentrics.eu takes 610ms 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
eu.acsbapp.com takes 544ms 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
51% of eu.acsbapp.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
app.usercentrics.eu takes 371ms 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 361ms 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 294ms 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 238ms 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
usercentrics.voestalpine.com takes 235ms 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 204ms 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
75% of content.jwplatform.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.