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.
12.40 s
Largest Contentful Paint Largest Contentful Paint — how long until the largest visible element loads. Under 2.5s is good.
19.97 s
Total Blocking Time Total Blocking Time — total time the main thread was blocked, preventing user input. Under 200ms is good.
1.51 s
Cumulative Layout Shift Cumulative Layout Shift — measures visual stability. How much the page layout shifts during loading. Under 0.1 is good.
0.023
Speed Index Speed Index — how quickly content is visually displayed during load. Under 3.4s is good.
16.48 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.
27.16 s
Page Load Progression
FPage Weight BudgetAction4.4 MB transferred, 65 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
DThird-Party ImpactAction100% third-party, 0 ms blockingFIX
FJS Execution CostAction9469ms total JS executionFIX
Main Thread Breakdown
| Script | Total | Scripting | Parse/Compile | Party |
|---|---|---|---|---|
| https://www.nationalacademies.org/publications/all | 2329ms | 25ms | 4ms | 3rd |
| Unattributable | 1553ms | 91ms | 0ms | 3rd |
| https://www.nationalacademies.org/build/assets/app-DrqUutlo.js | 1249ms | 254ms | 1ms | 3rd |
| https://scripts.clarity.ms/0.8.59-beta/clarity.js | 1134ms | 542ms | 11ms | 3rd |
| https://js.hs-analytics.net/analytics/1776807600000/49197025.js | 753ms | 534ms | 14ms | 3rd |
| https://admin-pipeline.upsun-us.observability-pipeline.blackfire.io/js/probe.js | 650ms | 465ms | 13ms | 3rd |
| https://js.hscollectedforms.net/collectedforms.js | 377ms | 341ms | 9ms | 3rd |
| https://cdn.cookielaw.org/scripttemplates/6.30.0/otBannerSdk.js | 366ms | 189ms | 43ms | 3rd |
| https://www.googletagmanager.com/gtag/js?id=G-95DFGJ1W4R&cx=c>m=4e64k0h2 | 358ms | 283ms | 72ms | 3rd |
| https://www.googletagmanager.com/gtm.js?id=GTM-K5ZR4BL2 | 334ms | 271ms | 57ms | 3rd |
Showing top 10 of 13 scripts
DPage Weight InventoryAction65 resources · 4.4 MB · 280 KB savings availableFIX
~279.9 KiB of savings available
| # | Resource | Type | Size | Cache | Unused | 3rd party | Issues |
|---|---|---|---|---|---|---|---|
| — | — | ||||||
| 65 resources | 4.4 MiB | ||||||
FHTTP CachingActionNo cache headersFIX
No Cache-Control header
Adding a Cache-Control header can significantly improve repeat-visit performance.
CImage OptimizationAction15 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.
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
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
CJS BundlesAction21 scripts, 280 KB unusedREVIEW
Downloaded but never executed on this page.
| Script | Size | Unused | Minified | Party |
|---|---|---|---|---|
| https://www.googletagmanager.com/gtag/js?id=G-95DFGJ1W4R&cx=c>m=4e64k0h2 | 170 KB | 69 KB (41%) | ✓ | 3rd |
| https://www.googletagmanager.com/gtm.js?id=GTM-K5ZR4BL2 | 138 KB | 62 KB (45%) | ✓ | 3rd |
| https://www.nationalacademies.org/build/assets/app-DrqUutlo.js | 72 KB | 53 KB (74%) | ✓ | 3rd |
| https://cdn.cookielaw.org/scripttemplates/6.30.0/otBannerSdk.js | 79 KB | 41 KB (52%) | ✓ | 3rd |
| https://admin-pipeline.upsun-us.observability-pipeline.blackfire.io/js/probe.js | 97 KB | 30 KB (31%) | ✓ | 3rd |
| https://cl.qualaroo.com/ki.js/80830/iOh.js | 60 KB | 24 KB (41%) | ✓ | 3rd |
| https://js.hscollectedforms.net/collectedforms.js | 26 KB | — | ✓ | 3rd |
| https://www.clarity.ms/tag/ux9mtioswv?ref=gtm | 1 KB | — | ✓ | 3rd |
| https://js.hsadspixel.net/pixels.js | 4 KB | — | ✓ | 3rd |
| https://js.hs-analytics.net/analytics/1776807600000/49197025.js | 42 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
CGreen HostingActionWhether the site is served from green-energy infrastructureREVIEW
Green Hosting
No green hosting detected
A+Text CompressionAll text resources are compressedPASS
A+Font Loading5 fonts (729 KB)PASS
Web fonts
5
729 KB total
Render-blocking
0
of 5
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
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 ~250 KB and ~500 ms
A+Resource CachingAll resources properly cachedPASS
A+Critical Rendering PathNo render-blocking resourcesPASS
A+Resource Hints6 hints, 0 missing preconnectsPASS
Current Resource Hints
6 resource hints configured
A+Render-Blocking ResourcesNo render-blocking resources detectedPASS
A+Third-Party ResourcesNo third-party resources detectedPASS
Network Waterfall65 requests over 13632msINFO
Third-Party Script CostPer-script blocking time, transfer cost, and cache headersINFO
| Script | Category | Execution | Transfer | Unused | Monthly Cost | Verdict |
|---|---|---|---|---|---|---|
www.nationalacademies.org www.nationalacademies.org | Other | 2329ms | 1410 KB | — | $31/mo | Costly |
Unattributable Unattributable | Other | 1553ms | 0 KB | — | $21/mo | Costly |
www.nationalacademies.org www.nationalacademies.org | Other | 1249ms | 72 KB | 74% | $17/mo | Costly |
Microsoft Clarity scripts.clarity.ms | Session Replay | 1134ms | 26 KB | — | $15/mo | Costly |
HubSpot Analytics js.hs-analytics.net | Analytics | 753ms | 42 KB | — | $10/mo | Costly |
admin-pipeline.upsun-us.observability-pipeline.blackfire.io admin-pipeline.upsun-us.observability-pipeline.blackfire.io | Other | 650ms | 97 KB | 31% | $9/mo | Costly |
js.hscollectedforms.net js.hscollectedforms.net | Other | 377ms | 26 KB | — | $5/mo | Costly |
OneTrust cdn.cookielaw.org | Consent | 366ms | 79 KB | 52% | $5/mo | Essential |
Google Tag Manager www.googletagmanager.com | Tag Manager | 358ms | 170 KB | 41% | $5/mo | Costly |
Google Tag Manager www.googletagmanager.com | Tag Manager | 334ms | 138 KB | 45% | $4/mo | Costly |
cl.qualaroo.com cl.qualaroo.com | Other | 239ms | 60 KB | 41% | $3/mo | Costly |
LinkedIn Insight snap.licdn.com | Advertising | 73ms | 19 KB | — | $1/mo | Optional |
OneTrust cdn.cookielaw.org | Consent | 54ms | 9 KB | — | $1/mo | Essential |
These scripts may cost more than they're worth
- www.nationalacademies.org adds 2329ms and costs ~$31/month
- Unattributable adds 1553ms and costs ~$21/month
- www.nationalacademies.org adds 1249ms and costs ~$17/month
- Microsoft Clarity adds 1134ms and costs ~$15/month
- HubSpot Analytics adds 753ms and costs ~$10/month
- admin-pipeline.upsun-us.observability-pipeline.blackfire.io adds 650ms and costs ~$9/month
- js.hscollectedforms.net adds 377ms and costs ~$5/month
- Google Tag Manager adds 358ms and costs ~$5/month
- Google Tag Manager adds 334ms and costs ~$4/month
- cl.qualaroo.com adds 239ms 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.nationalacademies.org takes 2329ms 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 1553ms 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.nationalacademies.org takes 1249ms 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
74% of www.nationalacademies.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
Microsoft Clarity takes 1134ms 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
HubSpot Analytics takes 753ms 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
admin-pipeline.upsun-us.observability-pipeline.blackfire.io takes 650ms 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
js.hscollectedforms.net takes 377ms 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
52% of OneTrust'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 358ms 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 334ms 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
cl.qualaroo.com takes 239ms 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