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https://www.anthropic.com

Performance

· 14 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
87
GRADE
B
FIX
2
REVIEW
4
PASS
6
INFO
2

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

Mobile Desktop
80
Performance Overall performance score (0–100) based on Core Web Vitals and other metrics. 90+ is good.
93
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.

1.62 s

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

2.35 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.

1.62 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.

2.35 s

Page Load Progression

397 ms
794 ms
1.2 s
1.6 s
2.0 s
2.4 s
2.8 s
3.2 s
Checks
14
6 PASS 4 REVIEW 2 FIX
D
Third-Party Impact
Action
95% third-party, 0 ms blocking
FIX
95% third-party, 0 ms blocking
Warning::
Third-party code accounts for 95% of page weight (1.0 MiB of 1.1 MiB)
Info::
Third-party blocking time is low (0 ms)
95%
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.
Info::
Last-Modified header present

No Cache-Control header

Adding a Cache-Control header can significantly improve repeat-visit performance.

B
Page Weight Budget
1.1 MB transferred, 28 requests
REVIEW
1.1 MB transferred, 28 requests
Info::
Page weighs 2.5 MB (1.1 MB transferred)
Info::
Fonts are 353 KB — consider subsetting or using system fonts
Subset fonts to include only used characters, or switch to system font stacks.
Got: 353 KB
Info::
28 HTTP requests
Info::
Estimated 0.23 g CO2 per page load
1.1 MB / 2.4 MB budget
1.1 MB transferred
28 requests
0.23 g CO2 per page load
JavaScript 364.3 KiB 33%
Fonts 352.9 KiB 32%
Images 279.6 KiB 25%
HTML 40.5 KiB 4%
CSS 36.9 KiB 3%
Other 27.5 KiB 2%
Other 3.9 KiB 0%
Other 1.7 KiB 0%
Other 651 B 0%
0 2.4 MB 4.9 MB
Under budget

Subset fonts to include only used characters, or switch to system font stacks.

Why this matters

Font payload is large — subset to used glyphs only, or fall back to system fonts (zero load time).

Source: web.dev font loading

B
JS Execution Cost
591ms total JS execution
REVIEW
591ms total JS execution
Warning::
https://cdn.prod.website-files.com/67ce28cfec624e2...: 254ms CPU time
Info::
https://www.anthropic.com/: 190ms CPU time
Info::
Unattributable: 85ms CPU time
Info::
https://cdn.intellimize.co/snippet/117895469.js: 62ms CPU time
Warning::
Third-party scripts: 402ms (68% of total)

Main Thread Breakdown

Script Evaluation 35% Other 29% Style & Layout 23% Script Parsing & Compilation 5% Rendering 5%
ScriptTotalScriptingParse/CompileParty
https://cdn.prod.website-files.com/67ce28cfec624e2b733f8a52/js/ant-brand.schunk.9ebbe4e3f7d60657.js254ms51ms6ms3rd
https://www.anthropic.com/190ms22ms3ms1st
Unattributable85ms25ms0ms3rd
https://cdn.intellimize.co/snippet/117895469.js62ms48ms8ms3rd
B
JS Bundles
12 scripts, 150 KB unused
REVIEW
12 scripts, 150 KB unused
Warning::
https://cdn.intellimize.co/snippet/117895469.js: 54 KB unused (64%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://cdn.prod.website-files.com/67ce28cfec624e2...: 54 KB unused (61%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://cdn.prod.website-files.com/67ce28cfec624e2...: 42 KB unused (50%)
Consider code splitting or tree shaking to reduce unused code.
Info::
Total unused JavaScript: 150 KB
150 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://cdn.intellimize.co/snippet/117895469.js85 KB54 KB (64%)✓3rd
https://cdn.prod.website-files.com/67ce28cfec624e2b733f8a52/js/ant-brand.schunk.f2efb3c5440a81cf.js89 KB54 KB (61%)✓3rd
https://cdn.prod.website-files.com/67ce28cfec624e2b733f8a52/js/ant-brand.schunk.9ebbe4e3f7d60657.js84 KB42 KB (50%)✓3rd
https://d3e54v103j8qbb.cloudfront.net/js/jquery-3.5.1.min.dc5e7f18c8.js?site=67ce28cfec624e2b733f8a5231 KB—✓3rd
https://cdn.prod.website-files.com/67ce28cfec624e2b733f8a52/js/ant-brand.a2ef681e.469cb5551b8867a1.js1 KB—✓3rd
https://cdn.prod.website-files.com/gsap/3.14.2/gsap.min.js29 KB—✓3rd
https://cdn.prod.website-files.com/gsap/3.14.2/TextPlugin.min.js4 KB—✓3rd
https://cdn.prod.website-files.com/gsap/3.14.2/SplitText.min.js4 KB—✓3rd
https://cdn.prod.website-files.com/gsap/3.14.2/ScrollTrigger.min.js18 KB—✓3rd
https://www.anthropic.com/scripts/webflow-privacy-banner.js8 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

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

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+
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
1 images, 0 KB saveable
PASS
1 images, 0 KB saveable
Warning::
https://cdn.prod.website-files.com/67ce28cfec624e2... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
1 images 280 KB
0 oversized -0 KB
0 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
3 fonts (353 KB)
PASS
3 fonts (353 KB)
Info::
3 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

3

353 KB total

Render-blocking

0

of 3

Dominant font-display

swap

Most common across fonts

Font loading timeline
Transfer FOIT (block) FOUT (swap)
0 ms 500 ms 1.0 s 1.5 s 2.0 s FCP 1.6 s LCP 2.3 shttps://cdn.prod.website-files.com/67ce28cfec624e2b733f8a52/69971a1551eb6cda0d656e8a_AnthropicSerif-Roman-Web.woff269971a1551eb6cda0d656e8... https://cdn.prod.website-files.com/67ce28cfec624e2b733f8a52/69971a1551eb6cda0d656e8a_AnthropicSerif-Roman-Web.woff2 — 171.8 KiB — 0 ms — font-display: swaphttps://cdn.prod.website-files.com/67ce28cfec624e2b733f8a52/69971a00a3295036497e1a28_AnthropicSans-Roman-Web.woff269971a00a3295036497e1a2... https://cdn.prod.website-files.com/67ce28cfec624e2b733f8a52/69971a00a3295036497e1a28_AnthropicSans-Roman-Web.woff2 — 116.1 KiB — 0 ms — font-display: swaphttps://cdn.prod.website-files.com/67ce28cfec624e2b733f8a52/69971a2e55d24d61bc045b1a_AnthropicMono-Roman-Web.woff269971a2e55d24d61bc045b1... https://cdn.prod.website-files.com/67ce28cfec624e2b733f8a52/69971a2e55d24d61bc045b1a_AnthropicMono-Roman-Web.woff2 — 65.0 KiB — 0 ms — font-display: swap
69971a1551eb6cda0d656e8... woff2 swap
Size 172 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
  • Subset this font — over 100 KB suggests Latin Extended or full glyph coverage that most pages don't need
69971a00a3295036497e1a2... woff2 swap
Size 116 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
  • Subset this font — over 100 KB suggests Latin Extended or full glyph coverage that most pages don't need
69971a2e55d24d61bc045b1... woff2 swap
Size 65 KB
Load time 0 ms
Start 0 ms
Risk FOUT — 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 ~144 KB and ~288 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
Network Waterfall
28 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
68% of JavaScript execution is third-party
First-party Third-party 402ms · 170KB · €4/mo
cdn.prod.website-files.com
Other
Costly
Execution 254ms
Transfer 84 KB
Unused 50%
Monthly Cost €3/mo
Unattributable
Other
Optional
Execution 85ms
Transfer 0 KB
Monthly Cost €1/mo
cdn.intellimize.co
Other
Optional
Execution 62ms
Transfer 85 KB
Unused 64%
Monthly Cost €1/mo

These scripts may cost more than they're worth

  • cdn.prod.website-files.com adds 254ms and costs ~€3/month

68% of JavaScript execution time comes from third-party scripts.

Why this matters

Third-party scripts (analytics, ads, social, A/B testing) often dominate execution time — every one is a perf-and-privacy tax.

Learn more ▾

Each third-party script is a black box: you don't control when it loads, what it executes, or how much it grows. They often account for a major share of total blocking time on average sites (HTTP Archive's Web Almanac documents the trend). Audit which ones you actually need, defer the rest, and use facade patterns (lite-youtube, lite-vimeo) for embedded media.

Source: web.dev / HTTP Archive Web Almanac

cdn.prod.website-files.com takes 254ms 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

64% of cdn.intellimize.co'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

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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