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
Image Optimization
Action
61 images, 0 KB saveable
REVIEW
61 images, 0 KB saveable
Warning::
!
https://m.media-amazon.com/images/I/71Fnaxdd0ML._S... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://m.media-amazon.com/images/I/21T6J5vadcL._S... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://m.media-amazon.com/images/I/31XibHdu7qL._S... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://m.media-amazon.com/images/I/31NAxziZIaL._S... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://m.media-amazon.com/images/I/71VkESCzXaL._S... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://m.media-amazon.com/images/I/31GC2rbXvuL._S... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://m.media-amazon.com/images/I/5183et3khDL._S... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://m.media-amazon.com/images/I/21eTN166MKL._S... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://m.media-amazon.com/images/I/51UBK7rkwNL._S... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
data:image/jpeg;base64,/9j/4AAQSkZJRgABAQAAAQABAAD... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://m.media-amazon.com/images/I/21uV8kWvzeL._S... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://m.media-amazon.com/images/I/311RqfH+RJL._S... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://m.media-amazon.com/images/I/61YVR3d3UfL._S... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://m.media-amazon.com/images/I/31dNA7uebXL._S... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://m.media-amazon.com/images/I/41h4lIRlFKL._S... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://m.media-amazon.com/images/I/31N8uaUzlKL._S... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://m.media-amazon.com/images/I/41q-wmyJUaL._S... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://m.media-amazon.com/images/I/31khqmn6+hL._S... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
61images364 KB
0oversized-0 KB
52legacy format
18missing 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
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
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.
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.
B
JavaScript Blocking
2 JS blocking issue(s) detected
REVIEW
2 JS blocking issue(s) detected
Warning::
!
1 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 8.2 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
22 fonts (722 KB)
PASS
22 fonts (722 KB)
Info::
i
22 font(s) use font-display: swap (FOUT risk but functional)
Web fonts
22
722 KB total
Render-blocking
0
of 22
Dominant font-display
swap
Most common across fonts
Font loading timeline
TransferFOIT (block)FOUT (swap)
KFPk-9IF4FqAqY-.woff2woff2swap
Size17 KB
Load time10 ms
Start783 ms
RiskFOUT — text flashes from fallback to web font
Wdqa3S7nfGc3Naj.woff2woff2swap
Size41 KB
Load time13 ms
Start783 ms
RiskFOUT — text flashes from fallback to web font
font-woff;charset=utf-8...woffswap
Size4 KB
Load time75 ms
Start1.2 s
RiskFOUT — text flashes from fallback to web font
Convert to woff2 for ~30% smaller file size
YixBCot3QJnxh4p.woff2woff2swap
Size92 KB
Load time31 ms
Start1.8 s
RiskFOUT — text flashes from fallback to web font
pDxWAF1pBB0dzGB.woff2woff2swap
Size17 KB
Load time22 ms
Start1.8 s
RiskFOUT — text flashes from fallback to web font
Dv1WQ5DdeMS5qP7.woff2woff2swap
Size28 KB
Load time26 ms
Start1.8 s
RiskFOUT — text flashes from fallback to web font
VjTR4RqBzY0mUYx.woff2woff2swap
Size22 KB
Load time30 ms
Start1.8 s
RiskFOUT — text flashes from fallback to web font
WOnTLzkiaEccV7F.woff2woff2swap
Size18 KB
Load time33 ms
Start1.8 s
RiskFOUT — text flashes from fallback to web font
2SazJx$EeTHfhMN.woff2woff2swap
Size18 KB
Load time59 ms
Start1.8 s
RiskFOUT — text flashes from fallback to web font
ozb5-CLHQWI6Soc.woff2woff2swap
Size29 KB
Load time102 ms
Start1.8 s
RiskFOUT — text flashes from fallback to web font
KwhNPG8Jz-Vz2X7.woff2woff2swap
Size23 KB
Load time65 ms
Start1.8 s
RiskFOUT — text flashes from fallback to web font
lZemoC3awOEEzLR.woff2woff2swap
Size41 KB
Load time141 ms
Start1.8 s
RiskFOUT — text flashes from fallback to web font
NvWNxKhmDbgI1lq.woff2woff2swap
Size42 KB
Load time141 ms
Start1.8 s
RiskFOUT — text flashes from fallback to web font
1Ep1kWVX5g73xrY.woff2woff2swap
Size41 KB
Load time140 ms
Start1.8 s
RiskFOUT — text flashes from fallback to web font
pnZF3$c0rgepEUt.woff2woff2swap
Size42 KB
Load time141 ms
Start1.8 s
RiskFOUT — text flashes from fallback to web font
-w6hwcDxlefrOYI.woff2woff2swap
Size42 KB
Load time141 ms
Start1.8 s
RiskFOUT — text flashes from fallback to web font
gyrV-mLs7VcgiFC.woff2woff2swap
Size34 KB
Load time138 ms
Start1.8 s
RiskFOUT — text flashes from fallback to web font
8AuIu4whVB5EMoJ.woff2woff2swap
Size35 KB
Load time139 ms
Start1.8 s
RiskFOUT — text flashes from fallback to web font
MexTn601PAhMvAn.woff2woff2swap
Size34 KB
Load time136 ms
Start1.8 s
RiskFOUT — text flashes from fallback to web font
rlTCFdyUZFR9mQI.woff2woff2swap
Size34 KB
Load time138 ms
Start1.8 s
RiskFOUT — text flashes from fallback to web font
ukoYNzKrqDRxhTq.woff2woff2swap
Size34 KB
Load time137 ms
Start1.8 s
RiskFOUT — text flashes from fallback to web font
1yLvxs7jafx7AW$.woff2woff2swap
Size35 KB
Load time134 ms
Start1.8 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 ~1 KB and ~2 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
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.
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
153 requests over 4412ms
INFO
HTML JavaScript CSS Images Fonts XHR/Fetch Other
Third-Party Script Cost
Per-script blocking time, transfer cost, and cache headers
INFO
82%of JavaScript execution is third-party
First-party Third-party6710ms · 1486KB · $89/mo
Script
Category
Execution
Transfer
Unused
Monthly Cost
Verdict
www.amazon.com
www.amazon.com
Other
2584ms
439 KB
—
$34/mo
Costly
d1nruqhae353qc.cloudfront.net
d1nruqhae353qc.cloudfront.net
Other
1283ms
63 KB
46%
$17/mo
Costly
1c5c1ecf7303.c0b160fb.us-east-1.token.awswaf.com
1c5c1ecf7303.c0b160fb.us-east-1.token.awswaf.com
Other
728ms
572 KB
55%
$10/mo
Costly
m.media-amazon.com
m.media-amazon.com
Other
519ms
1 KB
—
$7/mo
Costly
m.media-amazon.com
m.media-amazon.com
Other
367ms
98 KB
69%
$5/mo
Costly
m.media-amazon.com
m.media-amazon.com
Other
341ms
142 KB
70%
$5/mo
Costly
m.media-amazon.com
m.media-amazon.com
Other
243ms
21 KB
—
$3/mo
Costly
m.media-amazon.com
m.media-amazon.com
Other
191ms
3 KB
—
$3/mo
Optional
m.media-amazon.com
m.media-amazon.com
Other
157ms
59 KB
61%
$2/mo
Optional
m.media-amazon.com
m.media-amazon.com
Other
119ms
30 KB
—
$2/mo
Optional
m.media-amazon.com
m.media-amazon.com
Other
109ms
1 KB
—
$1/mo
Optional
m.media-amazon.com
m.media-amazon.com
Other
69ms
57 KB
42%
$1/mo
Optional
www.amazon.com
Other
Costly
Execution2584ms
Transfer439 KB
Monthly Cost$34/mo
d1nruqhae353qc.cloudfront.net
Other
Costly
Execution1283ms
Transfer63 KB
Unused46%
Monthly Cost$17/mo
1c5c1ecf7303.c0b160fb.us-east-1.token.awswaf.com
Other
Costly
Execution728ms
Transfer572 KB
Unused55%
Monthly Cost$10/mo
m.media-amazon.com
Other
Costly
Execution519ms
Transfer1 KB
Monthly Cost$7/mo
m.media-amazon.com
Other
Costly
Execution367ms
Transfer98 KB
Unused69%
Monthly Cost$5/mo
m.media-amazon.com
Other
Costly
Execution341ms
Transfer142 KB
Unused70%
Monthly Cost$5/mo
m.media-amazon.com
Other
Costly
Execution243ms
Transfer21 KB
Monthly Cost$3/mo
m.media-amazon.com
Other
Optional
Execution191ms
Transfer3 KB
Monthly Cost$3/mo
m.media-amazon.com
Other
Optional
Execution157ms
Transfer59 KB
Unused61%
Monthly Cost$2/mo
m.media-amazon.com
Other
Optional
Execution119ms
Transfer30 KB
Monthly Cost$2/mo
m.media-amazon.com
Other
Optional
Execution109ms
Transfer1 KB
Monthly Cost$1/mo
m.media-amazon.com
Other
Optional
Execution69ms
Transfer57 KB
Unused42%
Monthly Cost$1/mo
These scripts may cost more than they're worth
www.amazon.com adds 2584ms and costs ~$34/month
d1nruqhae353qc.cloudfront.net adds 1283ms and costs ~$17/month
1c5c1ecf7303.c0b160fb.us-east-1.token.awswaf.com adds 728ms and costs ~$10/month
m.media-amazon.com adds 519ms and costs ~$7/month
m.media-amazon.com adds 367ms and costs ~$5/month
m.media-amazon.com adds 341ms and costs ~$5/month
m.media-amazon.com adds 243ms and costs ~$3/month
82% 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
www.amazon.com takes 2584ms 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
d1nruqhae353qc.cloudfront.net takes 1283ms 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
1c5c1ecf7303.c0b160fb.us-east-1.token.awswaf.com takes 728ms 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
55% of 1c5c1ecf7303.c0b160fb.us-east-1.token.awswaf.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
m.media-amazon.com takes 519ms 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
m.media-amazon.com takes 367ms 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
69% of m.media-amazon.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
m.media-amazon.com takes 341ms 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
70% of m.media-amazon.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
m.media-amazon.com takes 243ms 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
61% of m.media-amazon.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.