Adding a Cache-Control header can significantly improve repeat-visit performance.
C
Page Weight Budget
Action
1.9 MB transferred, 61 requests
REVIEW
1.9 MB transferred, 61 requests
Info::
i
Page weighs 5.6 MB (1.9 MB transferred)
Warning::
!
JavaScript is 1.1 MB — consider code splitting or lazy loading
Large JavaScript bundles delay interactivity. Split code by route or defer non-critical scripts.
Got: 1.1 MB
Info::
i
61 HTTP requests
Info::
i
Estimated 0.41 g CO2 per page load
1.9 MBtransferred
61 requests
0.41 g CO2 per page load
JavaScript1.1 MiB56%
Images405.0 KiB20%
CSS152.9 KiB8%
Fonts147.5 KiB7%
Other115.5 KiB6%
HTML50.2 KiB3%
Other15.3 KiB1%
Other546 B0%
02.4 MB4.9 MB
Approaching limit
Large JavaScript bundles delay interactivity. Split code by route or defer non-critical scripts.
Why this matters
JavaScript bundle is large — code-split routes and lazy-load off-screen components to defer.
Source: web.dev
B
Third-Party Impact
50% third-party, 0 ms blocking
REVIEW
50% third-party, 0 ms blocking
Warning::
!
Third-party code accounts for 50% of page weight (1003.5 KiB of 1.9 MiB)
Info::
✓
Third-party blocking time is low (0 ms)
50%
50%
First-party Third-party
B
Image Optimization
33 images, 0 KB saveable
REVIEW
33 images, 0 KB saveable
Info::
✓
All images are well-optimized
33images405 KB
0oversized-0 KB
31legacy format
0missing dimensionsCLS risk
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
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.
B
JavaScript Blocking
2 JS blocking issue(s) detected
REVIEW
2 JS blocking issue(s) detected
Warning::
!
2 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 5.8 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
3 fonts (148 KB)
PASS
3 fonts (148 KB)
Info::
i
3 font(s) use font-display: swap (FOUT risk but functional)
Web fonts
3
148 KB total
Render-blocking
0
of 3
Dominant font-display
swap
Most common across fonts
Font loading timeline
TransferFOIT (block)FOUT (swap)
fontawesome-webfont.woff2woff2swap
Size76 KB
Load time92 ms
Start2.0 s
RiskFOUT — text flashes from fallback to web font
memvYaGs126MiZpBA-UvWbX...woff2swap
Size42 KB
Load time501 ms
Start2.0 s
RiskFOUT — text flashes from fallback to web font
memvYaGs126MiZpBA-UvWbX...woff2swap
Size30 KB
Load time393 ms
Start2.0 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)
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+
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::
✓
`ETag` present -- conditional GET supported
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
61 requests over 3583ms
INFO
HTML JavaScript CSS Images Fonts XHR/Fetch Other
Third-Party Script Cost
Per-script blocking time, transfer cost, and cache headers
INFO
11%of JavaScript execution is third-party
First-party Third-party626ms · 556KB · Kč77/mo
Script
Category
Execution
Transfer
Unused
Monthly Cost
Verdict
www.gstatic.com
www.gstatic.com
Other
279ms
375 KB
66%
Kč34/mo
Costly
Google Tag Manager
www.googletagmanager.com
Tag Manager
266ms
150 KB
44%
Kč33/mo
Costly
ajax.googleapis.com
ajax.googleapis.com
Other
81ms
32 KB
73%
Kč10/mo
Optional
www.gstatic.com
Other
Costly
Execution279ms
Transfer375 KB
Unused66%
Monthly CostKč34/mo
Google Tag Manager
Tag Manager
Costly
Execution266ms
Transfer150 KB
Unused44%
Monthly CostKč33/mo
ajax.googleapis.com
Other
Optional
Execution81ms
Transfer32 KB
Unused73%
Monthly CostKč10/mo
These scripts may cost more than they're worth
www.gstatic.com adds 279ms and costs ~Kč34/month
Google Tag Manager adds 266ms and costs ~Kč33/month
www.gstatic.com takes 279ms 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 www.gstatic.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
Google Tag Manager takes 266ms 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
73% of ajax.googleapis.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.