Skip to content
https://www.amazon.com

Performance

· 16 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
87
GRADE
B
FIX
2
REVIEW
3
PASS
9
INFO
2

Performance-focused optimization plan with CWV assessment, top offenders, and time estimates

Mobile Desktop
67
Performance Overall performance score (0–100) based on Core Web Vitals and other metrics. 90+ is good.
97
Accessibility Measures how accessible the page is for users with disabilities. Checks color contrast, ARIA labels, and semantic HTML.
100
Best Practices Checks for modern web development best practices including HTTPS, no console errors, and secure JavaScript.
92
SEO Measures basic SEO optimizations: meta tags, crawlability, link text, and mobile friendliness.

First Contentful Paint First Contentful Paint — how long until the browser renders the first piece of content. Under 1.8s is good.

4.78 s

Largest Contentful Paint Largest Contentful Paint — how long until the largest visible element loads. Under 2.5s is good.

4.96 s

Total Blocking Time Total Blocking Time — total time the main thread was blocked, preventing user input. Under 200ms is good.

191 ms

Cumulative Layout Shift Cumulative Layout Shift — measures visual stability. How much the page layout shifts during loading. Under 0.1 is good.

0.000

Speed Index Speed Index — how quickly content is visually displayed during load. Under 3.4s is good.

4.78 s

Time to Interactive Time to Interactive — how long until the page is fully interactive and responds to user input. Under 3.8s is good.

5.06 s

Page Load Progression

375 ms
750 ms
1.1 s
1.5 s
1.9 s
2.2 s
2.6 s
3.0 s
Checks
16
9 PASS 3 REVIEW 2 FIX
D
Third-Party Impact
Action
96% third-party, 0 ms blocking
FIX
96% third-party, 0 ms blocking
Warning::
Third-party code accounts for 96% of page weight (553.7 KiB of 576.1 KiB)
Info::
Third-party blocking time is low (0 ms)
96%
First-party Third-party
D
HTTP Caching
Action
no-store (uncacheable)
FIX
no-store (uncacheable)
Info::
Cache-Control: no-store prevents all caching
Intentional for dynamic content, but increases server load for every page view.
Got: no-store, max-age=0
Info::
No ETag or Last-Modified header
Conditional requests (304 Not Modified) are not possible without validators.
Cache-Control

no-store, max-age=0

DirectiveValueMeaning
no-store—Never cache this response
max-age0Cache for 0 seconds
C
JS Execution Cost
Action
1229ms total JS execution
REVIEW
1229ms total JS execution
Warning::
https://1c5c1ecf7303.c0b160fb.us-east-1.token.awsw...: 810ms CPU time
Info::
Unattributable: 241ms CPU time
Info::
https://www.amazon.com/: 102ms CPU time
Info::
https://images-na.ssl-images-amazon.com/images/G/0...: 76ms CPU time
Warning::
Third-party scripts: 1127ms (92% of total)

Main Thread Breakdown

Script Evaluation 65% Other 17% Script Parsing & Compilation 14%
ScriptTotalScriptingParse/CompileParty
https://1c5c1ecf7303.c0b160fb.us-east-1.token.awswaf.com/1c5c1ecf7303/d6a7a58005ec/04c5ab18cd2d/challenge.js810ms595ms164ms3rd
Unattributable241ms111ms0ms3rd
https://www.amazon.com/102ms48ms4ms1st
https://images-na.ssl-images-amazon.com/images/G/01/AUIClients/ClientSideMetricsAUIJavascript-51171fbdd28e1a7a61e922e8f0272af8bc74d37b.secure.variant-desktop-session-snapshot-keypress.min._V2_.js76ms51ms4ms3rd
C
JS Bundles
Action
5 scripts, 278 KB unused
REVIEW
5 scripts, 278 KB unused
Warning::
https://1c5c1ecf7303.c0b160fb.us-east-1.token.awsw...: 278 KB unused (56%)
Consider code splitting or tree shaking to reduce unused code.
Info::
Total unused JavaScript: 278 KB
278 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://1c5c1ecf7303.c0b160fb.us-east-1.token.awswaf.com/1c5c1ecf7303/d6a7a58005ec/04c5ab18cd2d/challenge.js500 KB278 KB (56%)✓3rd
https://images-na.ssl-images-amazon.com/images/G/01/csminstrumentation/csm-captcha-instrumentation.min.js2 KB—✓3rd
https://images-na.ssl-images-amazon.com/images/G/01/csminstrumentation/rd-script-6d68177fa6061598e9509dc4b5bdd08d.js1 KB—✓3rd
https://images-na.ssl-images-amazon.com/images/G/01/csminstrumentation/ue-base-1c399ad9886cab69575e1e5ee15c61a1._V313498596_.js4 KB—✓3rd
https://images-na.ssl-images-amazon.com/images/G/01/AUIClients/ClientSideMetricsAUIJavascript-51171fbdd28e1a7a61e922e8f0272af8bc74d37b.secure.variant-desktop-session-snapshot-keypress.min._V2_.js8 KB—✓3rd

Consider code splitting or tree shaking to reduce unused code.

Why this matters

This bundle has high unused code — code-split or tree-shake to ship only what executes.

Source: web.dev / Lighthouse coverage

C
Green Hosting
Action
Whether the site is served from green-energy infrastructure
REVIEW

Green Hosting

No green hosting detected

A+
Page Weight Budget
576 KB transferred, 16 requests
PASS
576 KB transferred, 16 requests
Info::
Page weighs 1.6 MB (576 KB transferred)
Warning::
JavaScript is 515 KB — consider code splitting or lazy loading
Large JavaScript bundles delay interactivity. Split code by route or defer non-critical scripts.
Got: 515 KB
Info::
16 HTTP requests
Info::
Estimated 0.12 g CO2 per page load
576 KB / 2.4 MB budget
576 KB transferred
16 requests
0.12 g CO2 per page load
JavaScript 514.6 KiB 89%
CSS 19.4 KiB 3%
Other 17.9 KiB 3%
Images 17.6 KiB 3%
HTML 4.5 KiB 1%
Other 2.0 KiB 0%
Other 177 B 0%
0 2.4 MB 4.9 MB
Under budget

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

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
Image Optimization
2 images, 0 KB saveable
PASS
2 images, 0 KB saveable
Warning::
https://fls-na.amazon.com/1/oc-csi/1/OP/requestId=... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
2 images 18 KB
0 oversized -0 KB
2 legacy format
1 missing dimensions CLS 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

A+
Font Loading
No web fonts (system fonts)
PASS
No web fonts (system fonts)
Info::
No web fonts loaded — system fonts are fastest
No web fonts loaded — system fonts are optimal.
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+
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
Network Waterfall
16 requests over 0ms
INFO

Performance analysis not available for this result.

Third-Party Script Cost
Per-script blocking time, transfer cost, and cache headers
INFO
92% of JavaScript execution is third-party
First-party Third-party 1127ms · 508KB · $15/mo
1c5c1ecf7303.c0b160fb.us-east-1.token.awswaf.com
Other
Costly
Execution 810ms
Transfer 500 KB
Unused 56%
Monthly Cost $11/mo
Unattributable
Other
Costly
Execution 241ms
Transfer 0 KB
Monthly Cost $3/mo
images-na.ssl-images-amazon.com
Other
Optional
Execution 76ms
Transfer 8 KB
Monthly Cost $1/mo

These scripts may cost more than they're worth

  • 1c5c1ecf7303.c0b160fb.us-east-1.token.awswaf.com adds 810ms and costs ~$11/month
  • Unattributable adds 241ms and costs ~$3/month

92% 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

1c5c1ecf7303.c0b160fb.us-east-1.token.awswaf.com takes 810ms 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

56% 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

Unattributable takes 241ms 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

How third-party costs are calculated

All checks on this page are automated. Results are estimates - run targeted manual reviews when the score affects a release decision.

Send Feedback