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.
8.16 s
Largest Contentful Paint Largest Contentful Paint — how long until the largest visible element loads. Under 2.5s is good.
17.77 s
Total Blocking Time Total Blocking Time — total time the main thread was blocked, preventing user input. Under 200ms is good.
870 ms
Cumulative Layout Shift Cumulative Layout Shift — measures visual stability. How much the page layout shifts during loading. Under 0.1 is good.
0.124
Speed Index Speed Index — how quickly content is visually displayed during load. Under 3.4s is good.
9.77 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.
19.56 s
Page Load Progression
DThird-Party ImpactAction100% third-party, 0 ms blockingFIX
FJS Execution CostAction4116ms total JS executionFIX
Main Thread Breakdown
| Script | Total | Scripting | Parse/Compile | Party |
|---|---|---|---|---|
| https://www.amnh.org/assets/ibexa/build/amnh-jquery.js?v=13484dfacf | 627ms | 450ms | 8ms | 3rd |
| Unattributable | 561ms | 79ms | 0ms | 3rd |
| https://www.googletagmanager.com/gtm.js?id=GTM-NXGG9T | 531ms | 438ms | 45ms | 3rd |
| https://www.amnh.org/assets/ibexa/build/amnh.js?v=13484dfacf | 379ms | 197ms | 31ms | 3rd |
| https://analytics.tiktok.com/i18n/pixel/static/main.MWE0ZWQ3ZWQwMA.js | 348ms | 211ms | 135ms | 3rd |
| https://www.googletagmanager.com/gtag/js?id=G-J0SCEJCMH8&cx=c>m=4e64k0h2 | 306ms | 245ms | 40ms | 3rd |
| https://www.amnh.org/ | 271ms | 47ms | 3ms | 3rd |
| https://www.amnh.org/cdn-cgi/challenge-platform/scripts/jsd/main.js | 220ms | 211ms | 2ms | 3rd |
| https://www.googletagmanager.com/gtag/destination?id=AW-810443679&cx=c>m=4e64k0h2 | 192ms | 161ms | 29ms | 3rd |
| https://try.abtasty.com/69faf49f49c795c18b4527e4a6e0fd15/main.4707d0d4020fb2b8faa4.js | 189ms | 161ms | 20ms | 3rd |
Showing top 10 of 15 scripts
DJS BundlesAction36 scripts, 429 KB unusedFIX
Downloaded but never executed on this page.
| Script | Size | Unused | Minified | Party |
|---|---|---|---|---|
| https://www.googletagmanager.com/gtag/js?id=G-J0SCEJCMH8&cx=c>m=4e64k0h2 | 177 KB | 65 KB (37%) | ✓ | 3rd |
| https://www.googletagmanager.com/gtag/destination?id=DC-9432320&cx=c>m=4e64k0h2 | 131 KB | 62 KB (48%) | ✓ | 3rd |
| https://www.googletagmanager.com/gtm.js?id=GTM-NXGG9T | 172 KB | 61 KB (35%) | ✓ | 3rd |
| https://www.googletagmanager.com/gtag/destination?id=AW-810443679&cx=c>m=4e64k0h2 | 144 KB | 58 KB (40%) | ✓ | 3rd |
| https://analytics.tiktok.com/i18n/pixel/static/main.MWE0ZWQ3ZWQwMA.js | 106 KB | 57 KB (54%) | ✓ | 3rd |
| https://www.amnh.org/assets/ibexa/build/amnh.js?v=13484dfacf | 91 KB | 49 KB (54%) | ✓ | 3rd |
| https://try.abtasty.com/69faf49f49c795c18b4527e4a6e0fd15/main.4707d0d4020fb2b8faa4.js | 66 KB | 43 KB (66%) | ✓ | 3rd |
| https://connect.facebook.net/en_US/fbevents.js | 97 KB | 34 KB (35%) | ✓ | 3rd |
| https://try.abtasty.com/shared/me.305288ec5969ff467545.js | 4 KB | — | ✓ | 3rd |
| https://collector-2328.tvsquared.com/tv2track.js | 0 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 InventoryAction159 resources · 2.0 MB · 429 KB savings availableFIX
~428.6 KiB of savings available
| # | Resource | Type | Size | Cache | Unused | 3rd party | Issues |
|---|---|---|---|---|---|---|---|
| — | — | ||||||
| 159 resources | 2.0 MiB | ||||||
FHTTP CachingActionNo cache headersFIX
No Cache-Control header
Adding a Cache-Control header can significantly improve repeat-visit performance.
CPage Weight BudgetAction2.0 MB transferred, 159 requestsREVIEW
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
CImage OptimizationAction51 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.
Performance issues directly impact user engagement and conversion rates.
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 Loading2 fonts (220 KB)PASS
Web fonts
2
220 KB total
Render-blocking
0
of 2
Dominant font-display
swap
Most common across fonts
Font loading timeline
- 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 ~110 KB and ~220 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 Waterfall159 requests over 3409msINFO
Third-Party Script CostPer-script blocking time, transfer cost, and cache headersINFO
| Script | Category | Execution | Transfer | Unused | Monthly Cost | Verdict |
|---|---|---|---|---|---|---|
www.amnh.org www.amnh.org | Other | 627ms | 31 KB | — | $8/mo | Costly |
Unattributable Unattributable | Other | 561ms | 0 KB | — | $7/mo | Costly |
Google Tag Manager www.googletagmanager.com | Tag Manager | 531ms | 172 KB | 35% | $7/mo | Costly |
www.amnh.org www.amnh.org | Other | 379ms | 91 KB | 54% | $5/mo | Costly |
analytics.tiktok.com analytics.tiktok.com | Other | 348ms | 106 KB | 54% | $5/mo | Costly |
Google Tag Manager www.googletagmanager.com | Tag Manager | 306ms | 177 KB | 37% | $4/mo | Costly |
www.amnh.org www.amnh.org | Other | 271ms | 18 KB | — | $4/mo | Costly |
www.amnh.org www.amnh.org | Other | 220ms | 0 KB | — | $3/mo | Costly |
Google Tag Manager www.googletagmanager.com | Tag Manager | 192ms | 144 KB | 40% | $3/mo | Optional |
try.abtasty.com try.abtasty.com | Other | 189ms | 66 KB | 66% | $2/mo | Optional |
Google Tag Manager www.googletagmanager.com | Tag Manager | 143ms | 131 KB | 48% | $2/mo | Optional |
Facebook Pixel connect.facebook.net | Advertising | 107ms | 97 KB | 35% | $1/mo | Optional |
Facebook Pixel connect.facebook.net | Advertising | 100ms | 45 KB | — | $1/mo | Optional |
www.amnh.org www.amnh.org | Other | 89ms | 4 KB | — | $1/mo | Optional |
LinkedIn Insight snap.licdn.com | Advertising | 54ms | 19 KB | — | $1/mo | Optional |
These scripts may cost more than they're worth
- www.amnh.org adds 627ms and costs ~$8/month
- Unattributable adds 561ms and costs ~$7/month
- Google Tag Manager adds 531ms and costs ~$7/month
- www.amnh.org adds 379ms and costs ~$5/month
- analytics.tiktok.com adds 348ms and costs ~$5/month
- Google Tag Manager adds 306ms and costs ~$4/month
- www.amnh.org adds 271ms and costs ~$4/month
- www.amnh.org adds 220ms 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.amnh.org takes 627ms 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 561ms 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 531ms 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.amnh.org takes 379ms 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.amnh.org'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
analytics.tiktok.com takes 348ms 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 analytics.tiktok.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
Google Tag Manager takes 306ms 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.amnh.org takes 271ms 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.amnh.org takes 220ms 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
66% of try.abtasty.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