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
1.6 MB transferred, 48 requests
REVIEW
1.6 MB transferred, 48 requests
Info::
i
Page weighs 3.3 MB (1.6 MB transferred)
Warning::
!
JavaScript is 793 KB — consider code splitting or lazy loading
Large JavaScript bundles delay interactivity. Split code by route or defer non-critical scripts.
Got: 793 KB
Info::
✓
48 HTTP requests
Info::
i
Estimated 0.34 g CO2 per page load
1.6 MBtransferred
48 requests
0.34 g CO2 per page load
JavaScript793.3 KiB48%
Images545.4 KiB33%
Fonts156.8 KiB9%
Other101.3 KiB6%
CSS44.6 KiB3%
HTML25.7 KiB2%
Other754 B0%
Other550 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
C
Image Optimization
Action
21 images, 0 KB saveable
REVIEW
21 images, 0 KB saveable
Warning::
!
https://www.analvids.com/assets/img/logo/analvids.... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.analvids.com/assets/img/agree18/analvi... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
21images545 KB
0oversized-0 KB
19legacy format
3missing 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
Performance issues directly impact user engagement and conversion rates.
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.
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
461ms total JS execution
PASS
461ms total JS execution
Info::
i
https://www.analvids.com/assets/js/app.js?rev=815: 177ms CPU time
Info::
i
Unattributable: 96ms CPU time
Info::
i
https://www.analvids.com/: 77ms CPU time
Info::
i
https://www.gstatic.com/recaptcha/releases/rL1ELiQ...: 60ms CPU time
Info::
i
https://www.googletagmanager.com/gtm.js?id=GTM-WWS...: 50ms CPU time
4 font(s) use font-display: swap (FOUT risk but functional)
Web fonts
4
157 KB total
Render-blocking
0
of 4
Dominant font-display
swap
Most common across fonts
Font loading timeline
TransferFOIT (block)FOUT (swap)
lato-v17-latin-regular....woff2swap
Size23 KB
Load time36 ms
Start214 ms
RiskFOUT — text flashes from fallback to web font
lato-v17-latin-700.woff2woff2swap
Size23 KB
Load time102 ms
Start216 ms
RiskFOUT — text flashes from fallback to web font
lato-v17-latin-900.woff2woff2swap
Size22 KB
Load time105 ms
Start216 ms
RiskFOUT — text flashes from fallback to web font
bootstrap-icons.woff2woff2swap
Size89 KB
Load time134 ms
Start216 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+
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.
Network Waterfall
48 requests over 933ms
INFO
HTML JavaScript CSS Images Fonts XHR/Fetch Other
Third-Party Script Cost
Per-script blocking time, transfer cost, and cache headers
INFO
79%of JavaScript execution is third-party
First-party Third-party365ms · 635KB · Kč45/mo
Script
Category
Execution
Transfer
Unused
Monthly Cost
Verdict
www.analvids.com
www.analvids.com
Other
177ms
107 KB
70%
Kč22/mo
Optional
www.analvids.com
www.analvids.com
Other
77ms
26 KB
—
Kč10/mo
Optional
www.gstatic.com
www.gstatic.com
Other
60ms
375 KB
66%
Kč7/mo
Optional
Google Tag Manager
www.googletagmanager.com
Tag Manager
50ms
128 KB
51%
Kč6/mo
Optional
www.analvids.com
Other
Optional
Execution177ms
Transfer107 KB
Unused70%
Monthly CostKč22/mo
www.analvids.com
Other
Optional
Execution77ms
Transfer26 KB
Monthly CostKč10/mo
www.gstatic.com
Other
Optional
Execution60ms
Transfer375 KB
Unused66%
Monthly CostKč7/mo
Google Tag Manager
Tag Manager
Optional
Execution50ms
Transfer128 KB
Unused51%
Monthly CostKč6/mo
79% 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
70% of www.analvids.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
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
51% 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.