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https://www.cohere.com

Performance

· 14 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
72
GRADE
C
FIX
4
REVIEW
3
PASS
5
INFO
2

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

Mobile Desktop
56
Performance Overall performance score (0–100) based on Core Web Vitals and other metrics. 90+ is good.
98
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.
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.

830 ms

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

2.46 s

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

520 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.

3.63 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.

7.62 s

Page Load Progression

583 ms
1.2 s
1.7 s
2.3 s
2.9 s
3.5 s
4.1 s
4.7 s
Checks
14
5 PASS 3 REVIEW 4 FIX
F
Page Weight Budget
Action
9.3 MB transferred, 180 requests
FIX
9.3 MB transferred, 180 requests
Critical::
Page weighs 23.0 MB (9.3 MB transferred)
Warning::
Images are 5.3 MB — compress or use modern formats
Convert images to WebP/AVIF and resize to display dimensions to reduce transfer size.
Got: 5.3 MB
Warning::
JavaScript is 1.8 MB — consider code splitting or lazy loading
Large JavaScript bundles delay interactivity. Split code by route or defer non-critical scripts.
Got: 1.8 MB
Info::
Fonts are 424 KB — consider subsetting or using system fonts
Subset fonts to include only used characters, or switch to system font stacks.
Got: 424 KB
Warning::
180 HTTP requests — consider bundling or reducing
Each request adds latency. Bundle small files, use sprites, or eliminate unnecessary requests.
Info::
Estimated 2.0 g CO2 per page load
9.3 MB / 2.4 MB budget
9.3 MB transferred
180 requests
2.0 g CO2 per page load
Images 5.3 MiB 57%
JavaScript 1.8 MiB 20%
Other 1.5 MiB 16%
Fonts 424.5 KiB 4%
Other 115.0 KiB 1%
HTML 69.4 KiB 1%
CSS 59.4 KiB 1%
Other 1.7 KiB 0%
Other 767 B 0%
Other 578 B 0%
Other 0 B 0%
0 2.4 MB 4.9 MB
Over budget

Convert images to WebP/AVIF and resize to display dimensions to reduce transfer size.

Why this matters

Image bandwidth is high — modern formats (WebP/AVIF) and resizing typically cut it 50%+.

Source: web.dev

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

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

Each request adds latency. Bundle small files, use sprites, or eliminate unnecessary requests.

Why this matters

High HTTP request count — bundling, sprite-ing, and HTTP/2 server push can reduce per-request overhead.

Source: web.dev

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 (9.3 MiB of 9.3 MiB)
Info::
Third-party blocking time is low (0 ms)
100%
First-party Third-party
F
JS Execution Cost
Action
4844ms total JS execution
FIX
4844ms total JS execution
Warning::
https://cohere.com/_next/static/chunks/79a5c8c7-8d...: 1555ms CPU time
Warning::
Unattributable: 889ms CPU time
Warning::
https://cohere.com/_next/static/chunks/3372-d43a11...: 683ms CPU time
Warning::
https://cohere.com/: 664ms CPU time
Warning::
https://cohere.com/_next/static/chunks/6815-980a79...: 412ms CPU time
Warning::
Third-party scripts: 4844ms (100% of total)

Main Thread Breakdown

Script Evaluation 54% Other 23% Style & Layout 8% Script Parsing & Compilation 6% Rendering 4% Garbage Collection 3%
ScriptTotalScriptingParse/CompileParty
https://cohere.com/_next/static/chunks/79a5c8c7-8d2e1a2c5f91247c.js1555ms1481ms12ms3rd
Unattributable889ms165ms0ms3rd
https://cohere.com/_next/static/chunks/3372-d43a11ed3cf32462.js683ms561ms8ms3rd
https://cohere.com/664ms29ms33ms3rd
https://cohere.com/_next/static/chunks/6815-980a790505f7a80c.js412ms41ms2ms3rd
https://www.googletagmanager.com/gtm.js?id=GTM-5W6STPC135ms109ms20ms3rd
https://cohere.com/_next/static/chunks/2d1400c4.33880f77071ba18f.js123ms111ms11ms3rd
https://www.googletagmanager.com/gtag/js?id=G-S33PXJMLTN&cx=c&gtm=4e646093ms68ms23ms3rd
https://cohere.com/_next/static/chunks/8043-a2ddd12a50120d22.js85ms3ms21ms3rd
https://cohere.com/_next/static/chunks/2526b07f-55ea6ad4fc5d8033.js84ms16ms9ms3rd

Showing top 10 of 12 scripts

F
JS Bundles
Action
61 scripts, 918 KB unused
FIX
61 scripts, 918 KB unused
Warning::
https://cohere.com/_next/static/chunks/8043-a2ddd1...: 115 KB unused (59%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://cohere.com/_next/static/chunks/35a9f203-8f...: 114 KB unused (95%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://t.contentsquare.net/uxa/9298be563ec16.js: 99 KB unused (78%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.googletagmanager.com/gtm.js?id=GTM-5W6...: 81 KB unused (49%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://cohere.com/_next/static/chunks/79a5c8c7-8d...: 76 KB unused (90%)
Consider code splitting or tree shaking to reduce unused code.
Info::
Total unused JavaScript: 918 KB
918 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://cohere.com/_next/static/chunks/8043-a2ddd12a50120d22.js197 KB115 KB (59%)✓3rd
https://cohere.com/_next/static/chunks/35a9f203-8f15a8e7798acbe6.js120 KB114 KB (95%)✓3rd
https://t.contentsquare.net/uxa/9298be563ec16.js127 KB99 KB (78%)✓3rd
https://www.googletagmanager.com/gtm.js?id=GTM-5W6STPC167 KB81 KB (49%)✓3rd
https://cohere.com/_next/static/chunks/79a5c8c7-8d2e1a2c5f91247c.js85 KB76 KB (90%)✓3rd
https://www.googletagmanager.com/gtag/js?id=G-S33PXJMLTN&cx=c&gtm=4e6460169 KB69 KB (41%)✓3rd
https://cohere.com/_next/static/chunks/2d1400c4.33880f77071ba18f.js78 KB46 KB (59%)✓3rd
https://cohere.com/_next/static/chunks/9979-24400beca6c34fe1.js49 KB42 KB (86%)✓3rd
https://cohere.com/_next/static/chunks/4069-0a5c37214518f62c.js57 KB41 KB (72%)✓3rd
https://cohere.com/_next/static/chunks/56ad31fa-0b649efe885326be.js76 KB41 KB (53%)✓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

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

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

B
Image Optimization
53 images, 0 KB saveable
REVIEW
53 images, 0 KB saveable
Info::
All images are well-optimized
53 images 5.3 MB
0 oversized -0 KB
28 legacy format
0 missing dimensions CLS risk
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::
No ETag or Last-Modified header
Conditional requests (304 Not Modified) are not possible without validators.
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+
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
6 fonts (424 KB)
PASS
6 fonts (424 KB)
Info::
6 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

6

424 KB total

Render-blocking

0

of 6

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 2.5 s FCP 830 ms LCP 2.5 shttps://cohere.com/_next/static/media/Unica77CohereWeb-Regular.e3763c16.woff2Unica77CohereWeb-Regula... https://cohere.com/_next/static/media/Unica77CohereWeb-Regular.e3763c16.woff2 — 114.5 KiB — 0 ms — font-display: swaphttps://cohere.com/_next/static/media/CohereIcon-Default.c14e50a0.woffCohereIcon-Default.c14e... https://cohere.com/_next/static/media/CohereIcon-Default.c14e50a0.woff — 17.4 KiB — 0 ms — font-display: swaphttps://cohere.com/_next/static/media/CohereMono-Regular.d3cdd41a.woff2CohereMono-Regular.d3cd... https://cohere.com/_next/static/media/CohereMono-Regular.d3cdd41a.woff2 — 24.1 KiB — 0 ms — font-display: swaphttps://cohere.com/_next/static/media/CohereText-Regular.870d4a70.woff2CohereText-Regular.870d... https://cohere.com/_next/static/media/CohereText-Regular.870d4a70.woff2 — 34.5 KiB — 0 ms — font-display: swaphttps://cohere.com/_next/static/media/Unica77CohereWeb-Bold.1195007b.woff2Unica77CohereWeb-Bold.1... https://cohere.com/_next/static/media/Unica77CohereWeb-Bold.1195007b.woff2 — 118.8 KiB — 0 ms — font-display: swaphttps://cohere.com/_next/static/media/Unica77CohereWeb-Medium.45bad867.woff2Unica77CohereWeb-Medium... https://cohere.com/_next/static/media/Unica77CohereWeb-Medium.45bad867.woff2 — 115.2 KiB — 0 ms — font-display: swap
Unica77CohereWeb-Regula... woff2 swap
Size 114 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
CohereIcon-Default.c14e... woff swap
Size 17 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
  • Convert to woff2 for ~30% smaller file size
CohereMono-Regular.d3cd... woff2 swap
Size 24 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
CohereText-Regular.870d... woff2 swap
Size 34 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
Unica77CohereWeb-Bold.1... woff2 swap
Size 119 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
Unica77CohereWeb-Medium... woff2 swap
Size 115 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
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 ~179 KB and ~358 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
180 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
100% of JavaScript execution is third-party
First-party Third-party 4844ms · 1029KB · €77/mo
cohere.com
Other
Costly
Execution 1555ms
Transfer 85 KB
Unused 90%
Monthly Cost €25/mo
Unattributable
Other
Costly
Execution 889ms
Transfer 0 KB
Monthly Cost €14/mo
cohere.com
Other
Costly
Execution 683ms
Transfer 51 KB
Unused 46%
Monthly Cost €11/mo
cohere.com
Other
Costly
Execution 664ms
Transfer 69 KB
Monthly Cost €11/mo
cohere.com
Other
Costly
Execution 412ms
Transfer 26 KB
Unused 84%
Monthly Cost €7/mo
Google Tag Manager
Tag Manager
Optional
Execution 135ms
Transfer 167 KB
Unused 49%
Monthly Cost €2/mo
cohere.com
Other
Optional
Execution 123ms
Transfer 78 KB
Unused 59%
Monthly Cost €2/mo
Google Tag Manager
Tag Manager
Optional
Execution 93ms
Transfer 169 KB
Unused 41%
Monthly Cost €1/mo
cohere.com
Other
Optional
Execution 85ms
Transfer 197 KB
Unused 59%
Monthly Cost €1/mo
cohere.com
Other
Optional
Execution 84ms
Transfer 54 KB
Monthly Cost €1/mo
cohere.com
Other
Optional
Execution 66ms
Transfer 6 KB
Monthly Cost €1/mo
t.contentsquare.net
Other
Optional
Execution 56ms
Transfer 127 KB
Unused 78%
Monthly Cost €1/mo

These scripts may cost more than they're worth

  • cohere.com adds 1555ms and costs ~€25/month
  • Unattributable adds 889ms and costs ~€14/month
  • cohere.com adds 683ms and costs ~€11/month
  • cohere.com adds 664ms and costs ~€11/month
  • cohere.com adds 412ms and costs ~€7/month

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

cohere.com takes 1555ms 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

90% of cohere.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 889ms 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

cohere.com takes 683ms 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

cohere.com takes 664ms 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

cohere.com takes 412ms 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

84% of cohere.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

59% of cohere.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

59% of cohere.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

78% of t.contentsquare.net'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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