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https://redux.js.org

Performance

· 14 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
93
GRADE
A
FIX
0
REVIEW
4
PASS
8
INFO
2

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

Mobile Desktop
90
Performance Overall performance score (0–100) based on Core Web Vitals and other metrics. 90+ is good.
100
Accessibility Measures how accessible the page is for users with disabilities. Checks color contrast, ARIA labels, and semantic HTML.
96
Best Practices Checks for modern web development best practices including HTTPS, no console errors, and secure JavaScript.
100
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.

1.05 s

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

2.13 s

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

366 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.

1.05 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.

3.06 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
14
8 PASS 4 REVIEW
B
Image Optimization
4 images, 0 KB saveable
REVIEW
4 images, 0 KB saveable
Warning::
https://redux.js.org/img/course-callout-mid.svg is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.netlify.com/img/global/badges/netlify-... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://redux.js.org/img/redux.svg is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
4 images 3 KB
0 oversized -0 KB
2 legacy format
3 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

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

C
JS Execution Cost
Action
1258ms total JS execution
REVIEW
1258ms total JS execution
Warning::
https://redux.js.org/assets/js/main.869dfa69.js: 808ms CPU time
Warning::
Unattributable: 280ms CPU time
Info::
https://redux.js.org/: 170ms CPU time
Info::
Third-party scripts: 280ms (22% of total)

Main Thread Breakdown

Script Evaluation 66% Other 17% Style & Layout 7% Script Parsing & Compilation 6%
ScriptTotalScriptingParse/CompileParty
https://redux.js.org/assets/js/main.869dfa69.js808ms715ms63ms1st
Unattributable280ms89ms0ms3rd
https://redux.js.org/170ms32ms3ms1st
C
Green Hosting
Action
Whether the site is served from green-energy infrastructure
REVIEW

Green Hosting

No green hosting detected

B
HTTP Caching
public,max-age=0,must-revalidate
REVIEW
public,max-age=0,must-revalidate
Info::
Cache-Control header is set
Got: public,max-age=0,must-revalidate
Info::
ETag present — enables conditional (304) responses
Cache-Control

public,max-age=0,must-revalidate

DirectiveValueMeaning
public—Any cache may store this response
max-age0Cache for 0 seconds
must-revalidate—Must recheck with server after expiry
A+
Page Weight Budget
324 KB transferred, 37 requests
PASS
324 KB transferred, 37 requests
Info::
Page weighs 841 KB (324 KB transferred)
Info::
37 HTTP requests
Info::
Estimated 0.07 g CO2 per page load
324 KB / 2.4 MB budget
324 KB transferred
37 requests
0.07 g CO2 per page load
JavaScript 197.6 KiB 61%
Other 70.9 KiB 22%
Other 31.0 KiB 10%
CSS 15.0 KiB 5%
HTML 6.0 KiB 2%
Images 3.4 KiB 1%
Other 0 B 0%
0 2.4 MB 4.9 MB
Under budget
A+
Third-Party Impact
1% third-party, 0 ms blocking
PASS
1% third-party, 0 ms blocking
Info::
Third-party code accounts for 1% of page weight (2.1 KiB of 323.9 KiB)
Info::
Third-party blocking time is low (0 ms)
99%
First-party Third-party
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
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+
JS Bundles
25 scripts, 49 KB unused
PASS
25 scripts, 49 KB unused
Warning::
https://redux.js.org/assets/js/main.869dfa69.js: 49 KB unused (35%)
Consider code splitting or tree shaking to reduce unused code.
Info::
Total unused JavaScript: 49 KB
49 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://redux.js.org/assets/js/main.869dfa69.js140 KB49 KB (35%)✓1st
https://redux.js.org/assets/js/17896441.cd4af64e.js12 KB—✓1st
https://redux.js.org/assets/js/5e95c892.7824562f.js0 KB—✓1st
https://redux.js.org/assets/js/c4f5d8e4.7180e135.js4 KB—✓1st
https://redux.js.org/assets/js/a7456010.7e3226f2.js0 KB—✓1st
https://redux.js.org/assets/js/c4f5d8e4.7180e135.js0 KB—✓1st
https://redux.js.org/assets/js/a7456010.7e3226f2.js0 KB—✓1st
https://redux-docs-umami.up.railway.app/script.js2 KB—✓3rd
https://redux.js.org/assets/js/aba21aa0.0aa4e8d5.js0 KB—✓1st
https://redux.js.org/assets/js/a7bd4aaa.42c83445.js1 KB—✓1st

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

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
33 hints, 0 missing preconnects
PASS
33 hints, 0 missing preconnects
Info::
Page uses 33 resource hint(s)

Current Resource Hints

preconnect
1
preload
2
dns-prefetch
—
prefetch
+20
30

33 resource hints configured

Network Waterfall
37 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
22% of JavaScript execution is third-party
First-party Third-party 280ms · 0KB · $4/mo
Unattributable
Other
Costly
Execution 280ms
Transfer 0 KB
Monthly Cost $4/mo

These scripts may cost more than they're worth

  • Unattributable adds 280ms and costs ~$4/month

Unattributable takes 280ms 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.

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