Performance
· 15 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.
894 ms
Largest Contentful Paint Largest Contentful Paint — how long until the largest visible element loads. Under 2.5s is good.
1.08 s
Total Blocking Time Total Blocking Time — total time the main thread was blocked, preventing user input. Under 200ms is good.
26 ms
Cumulative Layout Shift Cumulative Layout Shift — measures visual stability. How much the page layout shifts during loading. Under 0.1 is good.
0.005
Speed Index Speed Index — how quickly content is visually displayed during load. Under 3.4s is good.
984 ms
Time to Interactive Time to Interactive — how long until the page is fully interactive and responds to user input. Under 3.8s is good.
3.12 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 sDPage Weight BudgetAction2.2 MB transferred, 164 requestsFIX
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
DJS BundlesAction35 scripts, 427 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=4e64h1 | 178 KB | 65 KB (37%) | ✓ | 3rd |
| https://www.googletagmanager.com/gtag/destination?id=DC-9432320&cx=c>m=4e64h1 | 131 KB | 62 KB (48%) | ✓ | 3rd |
| https://www.googletagmanager.com/gtm.js?id=GTM-NXGG9T | 173 KB | 61 KB (35%) | ✓ | 3rd |
| https://www.googletagmanager.com/gtag/destination?id=AW-810443679&cx=c>m=4e64h1 | 145 KB | 58 KB (40%) | ✓ | 3rd |
| https://analytics.tiktok.com/i18n/pixel/static/main.MWE0ZWQ3ZWQwMA.js | 106 KB | 55 KB (52%) | ✓ | 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://analytics.tiktok.com/i18n/pixel/events.js?sdkid=CJ5AJ4RC77U5K7SP3UI0&lib=ttq | 3 KB | — | ✓ | 3rd |
| https://px4.ads.linkedin.com/collect?v=2&fmt=js&pid=2647066&time=1776814410189&url=https%3A%2F%2Fwww.amnh.org%2F&e_ipv6=AQLOpUYpFcBupAAAAZ2yZEp3Tk6D7REwklznK-WusfioshZeTuzx0MQmRtJ7RZHRQhSEyLNgG9tf | 1 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 InventoryAction164 resources · 2.2 MB · 427 KB savings availableFIX
~427.4 KiB of savings available
| # | Resource | Type | Size | Cache | Unused | 3rd party | Issues |
|---|---|---|---|---|---|---|---|
| — | — | ||||||
| 164 resources | 2.2 MiB | ||||||
FHTTP CachingActionNo cache headersFIX
No Cache-Control header
Adding a Cache-Control header can significantly improve repeat-visit performance.
CImage OptimizationAction58 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.
Performance issues directly impact user engagement and conversion rates.
BJS Execution Cost850ms total JS executionREVIEW
Main Thread Breakdown
| Script | Total | Scripting | Parse/Compile | Party |
|---|---|---|---|---|
| https://www.amnh.org/assets/ibexa/build/amnh-jquery.js?v=13484dfacf | 165ms | 115ms | 2ms | 3rd |
| Unattributable | 120ms | 7ms | 0ms | 3rd |
| https://www.amnh.org/assets/ibexa/build/amnh.js?v=13484dfacf | 110ms | 48ms | 6ms | 3rd |
| https://analytics.tiktok.com/i18n/pixel/static/main.MWE0ZWQ3ZWQwMA.js | 106ms | 67ms | 37ms | 3rd |
| https://www.googletagmanager.com/gtm.js?id=GTM-NXGG9T | 86ms | 72ms | 11ms | 3rd |
| https://www.googletagmanager.com/gtag/js?id=G-J0SCEJCMH8&cx=c>m=4e64h1 | 68ms | 58ms | 10ms | 3rd |
| https://www.amnh.org/ | 68ms | 8ms | 1ms | 3rd |
| https://www.amnh.org/cdn-cgi/challenge-platform/scripts/jsd/main.js | 67ms | 56ms | 0ms | 3rd |
| https://www.googletagmanager.com/gtag/destination?id=AW-810443679&cx=c>m=4e64h1 | 60ms | 53ms | 7ms | 3rd |
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+Green HostingWhether the site is served from green-energy infrastructurePASS
Green Hosting
This site is hosted on green energy infrastructure
Provider: Cloudflare
Network Waterfall164 requests over 2568msINFO
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 | 165ms | 31 KB | — | $2/mo | Optional |
Unattributable Unattributable | Other | 120ms | 0 KB | — | $2/mo | Optional |
www.amnh.org www.amnh.org | Other | 110ms | 91 KB | 54% | $1/mo | Optional |
analytics.tiktok.com analytics.tiktok.com | Other | 106ms | 106 KB | 52% | $1/mo | Optional |
Google Tag Manager www.googletagmanager.com | Tag Manager | 86ms | 173 KB | 35% | $1/mo | Optional |
Google Tag Manager www.googletagmanager.com | Tag Manager | 68ms | 178 KB | 37% | $1/mo | Optional |
www.amnh.org www.amnh.org | Other | 68ms | 18 KB | — | $1/mo | Optional |
www.amnh.org www.amnh.org | Other | 67ms | 0 KB | — | $1/mo | Optional |
Google Tag Manager www.googletagmanager.com | Tag Manager | 60ms | 145 KB | 40% | $1/mo | Optional |
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
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
52% 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