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
Page Weight Budget
Action
2.0 MB transferred, 53 requests
REVIEW
2.0 MB transferred, 53 requests
Info::
i
Page weighs 7.0 MB (2.0 MB transferred)
Warning::
!
JavaScript is 1.5 MB — consider code splitting or lazy loading
Large JavaScript bundles delay interactivity. Split code by route or defer non-critical scripts.
Got: 1.5 MB
Info::
i
53 HTTP requests
Info::
i
Estimated 0.41 g CO2 per page load
2.0 MBtransferred
53 requests
0.41 g CO2 per page load
JavaScript1.5 MiB74%
Fonts166.5 KiB8%
Images131.3 KiB6%
Other115.0 KiB6%
HTML56.7 KiB3%
Other38.7 KiB2%
CSS18.2 KiB1%
Other915 B0%
Other0 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
Image Optimization
7 images, 0 KB saveable
REVIEW
7 images, 0 KB saveable
Warning::
!
https://i.plug.it/local//sskin_ssk//img/inserisci_... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
7images131 KB
0oversized-0 KB
7legacy format
1missing 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
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::
!
7 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.
`document.write()` blocks all parallel resource discovery while it executes. Chrome explicitly disables the preload scanner on connections it judges slow when document.write is detected, serializing the entire subtree load. Almost always third-party ad / analytics legacy code; replacing with createElement + appendChild (or refusing to integrate the offending vendor) recovers significant load-time on mobile.
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
5 fonts (166 KB)
PASS
5 fonts (166 KB)
Info::
i
5 font(s) use font-display: swap (FOUT risk but functional)
Web fonts
5
166 KB total
Render-blocking
0
of 5
Dominant font-display
swap
Most common across fonts
Font loading timeline
TransferFOIT (block)FOUT (swap)
OpenSans.woff2woff2swap
Size33 KB
Load time25 ms
Start1.3 s
RiskFOUT — text flashes from fallback to web font
OpenSans-Semibold.woff2woff2swap
Size34 KB
Load time57 ms
Start1.3 s
RiskFOUT — text flashes from fallback to web font
OpenSans-Light.woff2woff2swap
Size34 KB
Load time39 ms
Start1.3 s
RiskFOUT — text flashes from fallback to web font
OpenSans-SemiboldItalic...woff2swap
Size32 KB
Load time43 ms
Start1.3 s
RiskFOUT — text flashes from fallback to web font
OpenSans-Bold.woff2woff2swap
Size34 KB
Load time52 ms
Start1.3 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
8 hints, 0 missing preconnects
PASS
8 hints, 0 missing preconnects
Info::
✓
Page uses 8 resource hint(s)
Current Resource Hints
preconnect
5
preload
3
dns-prefetch—
prefetch—
8 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
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::
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
53 requests over 2739ms
INFO
HTML JavaScript CSS Images Fonts XHR/Fetch Other
Third-Party Script Cost
Per-script blocking time, transfer cost, and cache headers
securepubads.g.doubleclick.net adds 237ms and costs ~€3/month
73% 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
Google Tag Manager takes 306ms 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
securepubads.g.doubleclick.net takes 237ms 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
76% of securepubads.g.doubleclick.net'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
78% of www.iolam.it'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
64% of c.amazon-adsystem.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.