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.
4.89 s
Largest Contentful Paint Largest Contentful Paint — how long until the largest visible element loads. Under 2.5s is good.
6.40 s
Total Blocking Time Total Blocking Time — total time the main thread was blocked, preventing user input. Under 200ms is good.
113 ms
Cumulative Layout Shift Cumulative Layout Shift — measures visual stability. How much the page layout shifts during loading. Under 0.1 is good.
0.008
Speed Index Speed Index — how quickly content is visually displayed during load. Under 3.4s is good.
6.14 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.
8.82 s
Page Load Progression
FPage Weight BudgetAction4.8 MB transferred, 78 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
DJS Execution CostAction2762ms total JS executionFIX
Main Thread Breakdown
| Script | Total | Scripting | Parse/Compile | Party |
|---|---|---|---|---|
| https://www.nationalacademies.org/publications/all | 939ms | 9ms | 1ms | 3rd |
| Unattributable | 407ms | 24ms | 0ms | 3rd |
| https://www.nationalacademies.org/build/assets/app-DrqUutlo.js | 375ms | 67ms | 0ms | 3rd |
| https://scripts.clarity.ms/0.8.59-beta/clarity.js | 232ms | 79ms | 3ms | 3rd |
| https://js.hs-analytics.net/analytics/1776807600000/49197025.js | 188ms | 127ms | 4ms | 3rd |
| https://admin-pipeline.upsun-us.observability-pipeline.blackfire.io/js/probe.js | 160ms | 120ms | 3ms | 3rd |
| https://cdn.cookielaw.org/scripttemplates/6.30.0/otBannerSdk.js | 128ms | 48ms | 11ms | 3rd |
| https://www.googletagmanager.com/gtag/js?id=G-95DFGJ1W4R&cx=c>m=4e64h1 | 114ms | 95ms | 18ms | 3rd |
| https://www.googletagmanager.com/gtm.js?id=GTM-K5ZR4BL2 | 91ms | 74ms | 15ms | 3rd |
| https://js.hscollectedforms.net/collectedforms.js | 77ms | 70ms | 3ms | 3rd |
Showing top 10 of 11 scripts
DPage Weight InventoryAction78 resources · 4.8 MB · 280 KB savings availableFIX
~279.7 KiB of savings available
| # | Resource | Type | Size | Cache | Unused | 3rd party | Issues |
|---|---|---|---|---|---|---|---|
| — | — | ||||||
| 78 resources | 4.8 MiB | ||||||
FHTTP CachingActionNo cache headersFIX
No Cache-Control header
Adding a Cache-Control header can significantly improve repeat-visit performance.
CImage OptimizationAction26 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
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
CJS BundlesAction22 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=4e64h1 | 170 KB | 68 KB (40%) | ✓ | 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 | 32 KB (33%) | ✓ | 3rd |
| https://cl.qualaroo.com/ki.js/80830/iOh.js | 61 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 HintsNo optimization neededPASS
Network Waterfall78 requests over 13240msINFO
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 | 939ms | 1410 KB | — | $12/mo | Costly |
Unattributable Unattributable | Other | 407ms | 0 KB | — | $5/mo | Costly |
www.nationalacademies.org www.nationalacademies.org | Other | 375ms | 72 KB | 74% | $5/mo | Costly |
Microsoft Clarity scripts.clarity.ms | Session Replay | 232ms | 26 KB | — | $3/mo | Costly |
HubSpot Analytics js.hs-analytics.net | Analytics | 188ms | 42 KB | — | $2/mo | Optional |
admin-pipeline.upsun-us.observability-pipeline.blackfire.io admin-pipeline.upsun-us.observability-pipeline.blackfire.io | Other | 160ms | 97 KB | 33% | $2/mo | Optional |
OneTrust cdn.cookielaw.org | Consent | 128ms | 79 KB | 52% | $2/mo | Essential |
Google Tag Manager www.googletagmanager.com | Tag Manager | 114ms | 170 KB | 40% | $2/mo | Optional |
Google Tag Manager www.googletagmanager.com | Tag Manager | 91ms | 138 KB | 45% | $1/mo | Optional |
js.hscollectedforms.net js.hscollectedforms.net | Other | 77ms | 26 KB | — | $1/mo | Optional |
cl.qualaroo.com cl.qualaroo.com | Other | 52ms | 61 KB | 41% | $1/mo | Optional |
These scripts may cost more than they're worth
- www.nationalacademies.org adds 939ms and costs ~$12/month
- Unattributable adds 407ms and costs ~$5/month
- www.nationalacademies.org adds 375ms and costs ~$5/month
- Microsoft Clarity adds 232ms 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 939ms 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 407ms 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 375ms 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 232ms 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