Performance
· 17 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.Performance-focused optimization plan with CWV assessment, top offenders, and time estimates
First Contentful Paint First Contentful Paint — how long until the browser renders the first piece of content. Under 1.8s is good.
3.44 s
Largest Contentful Paint Largest Contentful Paint — how long until the largest visible element loads. Under 2.5s is good.
8.19 s
Total Blocking Time Total Blocking Time — total time the main thread was blocked, preventing user input. Under 200ms is good.
2.48 s
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.
10.77 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.
45.90 s
Page Load Progression
FPage Weight BudgetAction11.9 MB transferred, 226 requestsFIX
Convert images to WebP/AVIF and resize to display dimensions to reduce transfer size.
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.
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.
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.
High HTTP request count — bundling, sprite-ing, and HTTP/2 server push can reduce per-request overhead.
Source: web.dev
DThird-Party ImpactAction100% third-party, 0 ms blockingFIX
FJS Execution CostAction10426ms total JS executionFIX
Main Thread Breakdown
| Script | Total | Scripting | Parse/Compile | Party |
|---|---|---|---|---|
| https://www.blockchain.com/_next/static/chunks/framework-945b357d4a851f4b.js | 1978ms | 1746ms | 41ms | 3rd |
| https://www.blockchain.com/ | 1656ms | 11ms | 3ms | 3rd |
| Unattributable | 1630ms | 29ms | 0ms | 3rd |
| https://www.blockchain.com/_next/static/chunks/94726e6d-2c3c75222ee1365a.js | 986ms | 191ms | 6ms | 3rd |
| https://www.blockchain.com/_next/static/chunks/2203-9aecd8ac8c703bd4.js | 741ms | 504ms | 1ms | 3rd |
| https://consent.cookiebot.com/uc.js | 668ms | 545ms | 31ms | 3rd |
| https://consent.cookiebot.com/975f91d8-13e1-415c-b65b-6305145fcef8/cc.js?renew=false&referer=www.blockchain.com&dnt=false&init=false | 574ms | 210ms | 35ms | 3rd |
| https://www.googletagmanager.com/gtag/js?id=G-9KS744RJG1&cx=c>m=4e64k0 | 519ms | 464ms | 52ms | 3rd |
| https://www.googletagmanager.com/gtm.js?id=GTM-KK99TPJ | 318ms | 249ms | 59ms | 3rd |
| https://www.blockchain.com/_next/static/chunks/pages/index-3a014644356b28d7.js | 270ms | 243ms | 19ms | 3rd |
Showing top 10 of 18 scripts
DJS BundlesAction36 scripts, 478 KB unusedFIX
Downloaded but never executed on this page.
| Script | Size | Unused | Minified | Party |
|---|---|---|---|---|
| https://www.blockchain.com/_next/static/chunks/3032-53816d7aa8881dbd.js | 108 KB | 93 KB (87%) | ✓ | 3rd |
| https://www.blockchain.com/_next/static/chunks/pages/_app-4ada073261323124.js | 139 KB | 74 KB (54%) | ✓ | 3rd |
| https://www.googletagmanager.com/gtm.js?id=GTM-KK99TPJ | 154 KB | 69 KB (45%) | ✓ | 3rd |
| https://www.googletagmanager.com/gtag/js?id=AW-339607297&cx=c>m=4e64k0 | 146 KB | 65 KB (45%) | ✓ | 3rd |
| https://www.googletagmanager.com/gtag/js?id=G-9KS744RJG1&cx=c>m=4e64k0 | 163 KB | 61 KB (37%) | ✓ | 3rd |
| https://www.blockchain.com/_next/static/chunks/3099-037149b14f08bf8f.js | 78 KB | 41 KB (54%) | ✓ | 3rd |
| https://www.blockchain.com/_next/static/chunks/ee8b1517-42d9e8ceb7c795d1.js | 53 KB | 29 KB (56%) | ✓ | 3rd |
| https://consent.cookiebot.com/975f91d8-13e1-415c-b65b-6305145fcef8/cc.js?renew=false&referer=www.blockchain.com&dnt=false&init=false | 106 KB | 25 KB (24%) | ✓ | 3rd |
| https://www.blockchain.com/_next/static/chunks/main-4f588273f2c76322.js | 44 KB | 21 KB (49%) | ✓ | 3rd |
| https://www.blockchain.com/_next/static/chunks/pages/index-3a014644356b28d7.js | 33 KB | — | ✓ | 3rd |
Consider code splitting or tree shaking to reduce unused code.
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.
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.
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.
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.
This bundle has high unused code — code-split or tree-shake to ship only what executes.
Source: web.dev / Lighthouse coverage
FPage Weight InventoryAction226 resources · 11.9 MB · 478 KB savings availableFIX
~478.0 KiB of savings available
| # | Resource | Type | Size | Cache | Unused | 3rd party | Issues |
|---|---|---|---|---|---|---|---|
| — | — | ||||||
| 226 resources | 11.9 MiB | ||||||
FHTTP CachingActionNo cache headersFIX
No Cache-Control header
Adding a Cache-Control header can significantly improve repeat-visit performance.
CImage OptimizationAction45 images, 0 KB saveableREVIEW
Set explicit width and height to prevent CLS.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
Image without explicit width/height — browser can't reserve space; CLS jumps when image loads.
Source: web.dev / Core Web Vitals
A+Text CompressionAll text resources are compressedPASS
A+Font Loading9 fonts (566 KB)PASS
Web fonts
9
566 KB total
Render-blocking
0
of 9
Dominant font-display
swap
Most common across fonts
Font loading timeline
- Convert to woff2 for ~30% smaller file size
- Convert to woff2 for ~30% smaller file size
- Convert to woff2 for ~30% smaller file size
- Convert to woff2 for ~30% smaller file size
- Convert to woff2 for ~30% smaller file size
- Subset this font — over 100 KB suggests Latin Extended or full glyph coverage that most pages don't need
- Subset this font — over 100 KB suggests Latin Extended or full glyph coverage that most pages don't need
- Subset this font — over 100 KB suggests Latin Extended or full glyph coverage that most pages don't need
- 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 ~259 KB and ~518 ms
A+Resource CachingAll resources properly cachedPASS
A+Critical Rendering PathNo render-blocking resourcesPASS
A+Resource HintsNo optimization neededPASS
A+Render-Blocking ResourcesNo render-blocking resources detectedPASS
A+Third-Party ResourcesNo third-party resources detectedPASS
A+Green HostingWhether the site is served from green-energy infrastructurePASS
Green Hosting
This site is hosted on green energy infrastructure
Provider: Cloudflare
Network Waterfall226 requests over 3239msINFO
Third-Party Script CostPer-script blocking time, transfer cost, and cache headersINFO
| Script | Category | Execution | Transfer | Unused | Monthly Cost | Verdict |
|---|---|---|---|---|---|---|
www.blockchain.com www.blockchain.com | Other | 1978ms | 46 KB | — | $26/mo | Costly |
www.blockchain.com www.blockchain.com | Other | 1656ms | 117 KB | — | $22/mo | Costly |
Unattributable Unattributable | Other | 1630ms | 0 KB | — | $22/mo | Costly |
www.blockchain.com www.blockchain.com | Other | 986ms | 21 KB | — | $13/mo | Costly |
www.blockchain.com www.blockchain.com | Other | 741ms | 5 KB | — | $10/mo | Costly |
consent.cookiebot.com consent.cookiebot.com | Other | 668ms | 27 KB | — | $9/mo | Costly |
consent.cookiebot.com consent.cookiebot.com | Other | 574ms | 106 KB | 24% | $8/mo | Costly |
Google Tag Manager www.googletagmanager.com | Tag Manager | 519ms | 163 KB | 37% | $7/mo | Costly |
Google Tag Manager www.googletagmanager.com | Tag Manager | 318ms | 154 KB | 45% | $4/mo | Costly |
www.blockchain.com www.blockchain.com | Other | 270ms | 33 KB | — | $4/mo | Costly |
Google Tag Manager www.googletagmanager.com | Tag Manager | 256ms | 146 KB | 45% | $3/mo | Costly |
www.blockchain.com www.blockchain.com | Other | 242ms | 139 KB | 54% | $3/mo | Costly |
www.blockchain.com www.blockchain.com | Other | 177ms | 53 KB | 56% | $2/mo | Optional |
www.blockchain.com www.blockchain.com | Other | 128ms | 44 KB | 49% | $2/mo | Optional |
websdk.appsflyersdk.com websdk.appsflyersdk.com | Other | 88ms | 15 KB | — | $1/mo | Optional |
www.blockchain.com www.blockchain.com | Other | 73ms | 3 KB | — | $1/mo | Optional |
www.blockchain.com www.blockchain.com | Other | 62ms | 78 KB | 54% | $1/mo | Optional |
d2hrivdxn8ekm8.cloudfront.net d2hrivdxn8ekm8.cloudfront.net | Other | 62ms | 15 KB | — | $1/mo | Optional |
These scripts may cost more than they're worth
- www.blockchain.com adds 1978ms and costs ~$26/month
- www.blockchain.com adds 1656ms and costs ~$22/month
- Unattributable adds 1630ms and costs ~$22/month
- www.blockchain.com adds 986ms and costs ~$13/month
- www.blockchain.com adds 741ms and costs ~$10/month
- consent.cookiebot.com adds 668ms and costs ~$9/month
- consent.cookiebot.com adds 574ms and costs ~$8/month
- Google Tag Manager adds 519ms and costs ~$7/month
- Google Tag Manager adds 318ms and costs ~$4/month
- www.blockchain.com adds 270ms and costs ~$4/month
- Google Tag Manager adds 256ms and costs ~$3/month
- www.blockchain.com adds 242ms and costs ~$3/month
100% of JavaScript execution time is spent on third-party scripts. Consider auditing which scripts are essential.
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
www.blockchain.com takes 1978ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
www.blockchain.com takes 1656ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
Unattributable takes 1630ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
www.blockchain.com takes 986ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
www.blockchain.com takes 741ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
consent.cookiebot.com takes 668ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
consent.cookiebot.com takes 574ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
Google Tag Manager takes 519ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
Google Tag Manager takes 318ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
www.blockchain.com takes 270ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
Google Tag Manager takes 256ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
www.blockchain.com takes 242ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
54% of www.blockchain.com's code is unused. The script may be loading features you don't use.
Bundle has high unused-code ratio — tree-shaking and route-splitting recover the wasted bytes.
Source: web.dev
56% of www.blockchain.com's code is unused. The script may be loading features you don't use.
Bundle has high unused-code ratio — tree-shaking and route-splitting recover the wasted bytes.
Source: web.dev
54% of www.blockchain.com's code is unused. The script may be loading features you don't use.
Bundle has high unused-code ratio — tree-shaking and route-splitting recover the wasted bytes.
Source: web.dev