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https://random.org

Performance

· 17 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
93
GRADE
A
FIX
2
REVIEW
1
PASS
12
INFO
2

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

Mobile Desktop
99
Performance Overall performance score (0–100) based on Core Web Vitals and other metrics. 90+ is good.
65
Accessibility Measures how accessible the page is for users with disabilities. Checks color contrast, ARIA labels, and semantic HTML.
92
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.

1.61 s

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

1.61 s

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

0 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.

1.61 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.

1.61 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
17
12 PASS 1 REVIEW 2 FIX
D
Third-Party Impact
Action
100% third-party, 0 ms blocking
FIX
100% third-party, 0 ms blocking
Warning::
Third-party code accounts for 100% of page weight (56.0 KiB of 56.2 KiB)
Info::
Third-party blocking time is low (0 ms)
100%
First-party Third-party
F
HTTP Caching
Action
No cache headers
FIX
No cache headers
Warning::
No Cache-Control header found
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.

B
Image Optimization
4 images, 0 KB saveable
REVIEW
4 images, 0 KB saveable
Info::
All images are well-optimized
4 images 29 KB
0 oversized -0 KB
4 legacy format
0 missing dimensions CLS risk
A+
Page Weight Budget
56 KB transferred, 16 requests
PASS
56 KB transferred, 16 requests
Info::
Page weighs 144 KB (56 KB transferred)
Info::
16 HTTP requests
Info::
Estimated 0.01 g CO2 per page load
56 KB / 2.4 MB budget
56 KB transferred
16 requests
0.01 g CO2 per page load
Images 28.9 KiB 51%
JavaScript 12.8 KiB 23%
HTML 10.3 KiB 18%
CSS 3.0 KiB 5%
Other 1.0 KiB 2%
Other 189 B 0%
0 2.4 MB 4.9 MB
Under budget
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
247ms total JS execution
PASS
247ms total JS execution
Info::
Unattributable: 106ms CPU time
Info::
https://www.random.org/: 89ms CPU time
Info::
https://static.cloudflareinsights.com/beacon.min.j...: 52ms CPU time
Warning::
Third-party scripts: 247ms (100% of total)

Main Thread Breakdown

Other 44% Style & Layout 23% Script Evaluation 21% Parse HTML & CSS 6% Rendering 3%
ScriptTotalScriptingParse/CompileParty
Unattributable106ms4ms0ms3rd
https://www.random.org/89ms4ms1ms3rd
https://static.cloudflareinsights.com/beacon.min.js/v8c78df7c7c0f484497ecbca7046644da177152312451652ms32ms4ms3rd
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
3 scripts, 0 KB unused
PASS
3 scripts, 0 KB unused
0 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://www.random.org/js/random.js2 KB—✓3rd
https://static.cloudflareinsights.com/beacon.min.js/v8c78df7c7c0f484497ecbca7046644da177152312451611 KB—✓3rd
https://static.cloudflareinsights.com/beacon.min.js/v8c78df7c7c0f484497ecbca7046644da17715231245160 KB—✓3rd
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
Page Weight Inventory
16 resources · 56 KB · 0 KB savings available
PASS
16 resources · 56 KB · 0 KB savings available
Info::
Within 1MB page-weight target
Got: 56 KB
Warning::
15 third-party resources (100% of weight)
16 resources · 56.2 KiB · 15 third-party Within 1MB page-weight target
Image 52% · 29.4 KiB
JavaScript 23% · 12.8 KiB
Document 19% · 10.6 KiB
CSS 5% · 3.0 KiB
Other 1% · 375 B
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+
Green Hosting
Whether the site is served from green-energy infrastructure
PASS

Green Hosting

This site is hosted on green energy infrastructure

Provider: Cloudflare

Network Waterfall
16 requests over 325ms
INFO
0 ms 500 ms 1.0 s 1.5 s FCP 1.6 s LCP 1.6 shttps://random.org// https://random.org/ — 301 — 186 B — 71 ms — h2https://www.random.org/www.random.org/ https://www.random.org/ — 200 — 6.8 KiB — 54 ms — h2https://www.random.org/css/style.csswww.random.org/css/style.css https://www.random.org/css/style.css — 200 — 2.0 KiB — 27 ms — h2https://www.random.org/css/mobile-style.csswww.random.org/css/mobile-style.css https://www.random.org/css/mobile-style.css — 200 — 1003 B — 45 ms — h2https://www.random.org/js/random.jswww.random.org/js/random.js https://www.random.org/js/random.js — 200 — 2.1 KiB — 25 ms — h2https://www.random.org/graphics/nuvola/learn.pngwww.random.org/graphics/nuvola/lear... https://www.random.org/graphics/nuvola/learn.png — 200 — 11.0 KiB — 27 ms — h2https://www.random.org/graphics/nuvola/graph.pngwww.random.org/graphics/nuvola/grap... https://www.random.org/graphics/nuvola/graph.png — 200 — 7.9 KiB — 26 ms — h2https://www.random.org/graphics/nuvola/help.gifwww.random.org/graphics/nuvola/help... https://www.random.org/graphics/nuvola/help.gif — 200 — 5.8 KiB — 27 ms — h2https://static.cloudflareinsights.com/beacon.min.js/v8c78df7c7c0f484497ecbca7046644da1771523124516static.cloudflareinsights.com/beaco... https://static.cloudflareinsights.com/beacon.min.js/v8c78df7c7c0f484497ecbca7046644da1771523124516 — 200 — 10.7 KiB — 101 ms — h2https://www.random.org/widgets/integers/iframe.php?title=True+Random+Number+Generator&buttontxt=Generate&width=160&height=230&border=on&bgcolor=%23FFFFFF&txtcolor=%23777777&altbgcolor=%23CCCCFFA&alttxtcolor=%23000000&defaultmin=1&defaultmax=100&fixed=offwww.random.org/widgets/integers/ifr... https://www.random.org/widgets/integers/iframe.php?title=True+Random+Number+Generator&buttontxt=Generate&width=160&height=230&border=on&bgcolor=%23FFFFFF&txtcolor=%23777777&altbgcolor=%23CCCCFFA&alttxtcolor=%23000000&defaultmin=1&defaultmax=100&fixed=off — 301 — 328 B — 44 ms — h2https://www.random.org/graphics/rdo-logo-300x44.pngwww.random.org/graphics/rdo-logo-30... https://www.random.org/graphics/rdo-logo-300x44.png — 200 — 4.2 KiB — 26 ms — h2https://www.random.org/widgets/integers/iframe?title=True+Random+Number+Generator&buttontxt=Generate&width=160&height=230&border=on&bgcolor=%23FFFFFF&txtcolor=%23777777&altbgcolor=%23CCCCFFA&alttxtcolor=%23000000&defaultmin=1&defaultmax=100&fixed=offwww.random.org/widgets/integers/ifr... https://www.random.org/widgets/integers/iframe?title=True+Random+Number+Generator&buttontxt=Generate&width=160&height=230&border=on&bgcolor=%23FFFFFF&txtcolor=%23777777&altbgcolor=%23CCCCFFA&alttxtcolor=%23000000&defaultmin=1&defaultmax=100&fixed=off — 200 — 3.4 KiB — 37 ms — h2https://static.cloudflareinsights.com/beacon.min.js/v8c78df7c7c0f484497ecbca7046644da1771523124516static.cloudflareinsights.com/beaco... https://static.cloudflareinsights.com/beacon.min.js/v8c78df7c7c0f484497ecbca7046644da1771523124516 — 200 — 0 B — 11 ms — h2https://www.random.org/cdn-cgi/rum?www.random.org/cdn-cgi/rum? https://www.random.org/cdn-cgi/rum? — 204 — 151 B — 21 ms — h2https://www.random.org/cdn-cgi/rum?www.random.org/cdn-cgi/rum? https://www.random.org/cdn-cgi/rum? — 204 — 38 B — 20 ms — h2https://www.random.org/favicon.icowww.random.org/favicon.ico https://www.random.org/favicon.ico — 200 — 553 B — 25 ms — h2
HTML JavaScript CSS Images Fonts XHR/Fetch Other
Third-Party Script Cost
Per-script blocking time, transfer cost, and cache headers
INFO
100% of JavaScript execution is third-party
First-party Third-party 247ms · 7KB · €3/mo
Unattributable
Other
Optional
Execution 106ms
Transfer 0 KB
Monthly Cost €1/mo
www.random.org
Other
Optional
Execution 89ms
Transfer 7 KB
Monthly Cost €1/mo
static.cloudflareinsights.com
Other
Optional
Execution 52ms
Transfer 0 KB
Monthly Cost €1/mo

100% 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

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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