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Performance

· 17 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
79
GRADE
C
FIX
5
REVIEW
2
PASS
8
INFO
2

Performance-focused optimization plan with CWV assessment, top offenders, and time estimates

Mobile Desktop
57
Performance Overall performance score (0–100) based on Core Web Vitals and other metrics. 90+ is good.
90
Accessibility Measures how accessible the page is for users with disabilities. Checks color contrast, ARIA labels, and semantic HTML.
96
Best Practices Checks for modern web development best practices including HTTPS, no console errors, and secure JavaScript.
100
SEO Measures basic SEO optimizations: meta tags, crawlability, link text, and mobile friendliness.

First Contentful Paint First Contentful Paint — how long until the browser renders the first piece of content. Under 1.8s is good.

2.41 s

Largest Contentful Paint Largest Contentful Paint — how long until the largest visible element loads. Under 2.5s is good.

11.83 s

Total Blocking Time Total Blocking Time — total time the main thread was blocked, preventing user input. Under 200ms is good.

454 ms

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.

4.82 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.

11.83 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 s
Checks
17
8 PASS 2 REVIEW 5 FIX
D
Third-Party Impact
Action
100% third-party, 0 ms blocking
FIX
100% third-party, 0 ms blocking
Warning::
Third-party code accounts for 100% of page weight (1.4 MiB of 1.4 MiB)
Info::
Third-party blocking time is low (0 ms)
100%
First-party Third-party
D
JS Execution Cost
Action
2450ms total JS execution
FIX
2450ms total JS execution
Warning::
https://www.nber.org/: 690ms CPU time
Warning::
https://cdnjs.cloudflare.com/ajax/libs/d3/6.7.0/d3...: 468ms CPU time
Warning::
https://www.nber.org/themes/custom/nber/assets/bui...: 300ms CPU time
Warning::
Unattributable: 277ms CPU time
Info::
https://www.googletagmanager.com/gtm.js?id=GTM-MVR...: 249ms CPU time
Warning::
Third-party scripts: 2450ms (100% of total)

Main Thread Breakdown

Script Evaluation 38% Other 23% Style & Layout 14% Rendering 12% Script Parsing & Compilation 9%
ScriptTotalScriptingParse/CompileParty
https://www.nber.org/690ms11ms1ms3rd
https://cdnjs.cloudflare.com/ajax/libs/d3/6.7.0/d3.min.js468ms126ms28ms3rd
https://www.nber.org/themes/custom/nber/assets/build/js/index-generated.js?tduart300ms262ms22ms3rd
Unattributable277ms7ms0ms3rd
https://www.googletagmanager.com/gtm.js?id=GTM-MVRPF7C249ms202ms40ms3rd
https://www.googletagmanager.com/gtag/js?id=G-3Y05NLKEBB&cx=c&gtm=4e64h1235ms188ms40ms3rd
https://www.nber.org/themes/custom/nber/assets/build/js/libraries-generated.js?tduart114ms12ms102ms3rd
https://www.nber.org/modules/custom/nber_charts/js/unemployment-graphic.js?v=161ms56ms1ms3rd
https://www.google-analytics.com/analytics.js55ms44ms4ms3rd
D
JS Bundles
Action
16 scripts, 361 KB unused
FIX
16 scripts, 361 KB unused
Warning::
https://www.nber.org/themes/custom/nber/assets/bui...: 147 KB unused (54%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.googletagmanager.com/gtag/js?id=G-3Y05...: 63 KB unused (41%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.googletagmanager.com/gtm.js?id=GTM-MVR...: 63 KB unused (44%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://cdnjs.cloudflare.com/ajax/libs/d3/6.7.0/d3...: 55 KB unused (75%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.nber.org/themes/custom/nber/assets/bui...: 33 KB unused (64%)
Consider code splitting or tree shaking to reduce unused code.
Info::
Total unused JavaScript: 361 KB
361 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://www.nber.org/themes/custom/nber/assets/build/js/libraries-generated.js?tduart273 KB147 KB (54%)✓3rd
https://www.googletagmanager.com/gtag/js?id=G-3Y05NLKEBB&cx=c&gtm=4e64h1156 KB63 KB (41%)✓3rd
https://www.googletagmanager.com/gtm.js?id=GTM-MVRPF7C144 KB63 KB (44%)✓3rd
https://cdnjs.cloudflare.com/ajax/libs/d3/6.7.0/d3.min.js73 KB55 KB (75%)✓3rd
https://www.nber.org/themes/custom/nber/assets/build/js/index-generated.js?tduart51 KB33 KB (64%)✓3rd
https://www.nber.org/core/misc/drupal.init.js?v=10.4.91 KB—✓3rd
https://www.nber.org/core/assets/vendor/once/once.min.js?v=1.0.11 KB—✓3rd
https://www.nber.org/modules/contrib/lazy/js/lazy.js?v=10.4.91 KB—✓3rd
https://www.nber.org/core/misc/drupal.js?v=10.4.97 KB—✗3rd
https://www.nber.org/core/misc/drupalSettingsLoader.js?v=10.4.91 KB—✓3rd

Consider code splitting or tree shaking to reduce unused code.

Why this matters

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.

Why this matters

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.

Why this matters

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.

Why this matters

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.

Why this matters

This bundle has high unused code — code-split or tree-shake to ship only what executes.

Source: web.dev / Lighthouse coverage

D
Page Weight Inventory
Action
59 resources · 1.4 MB · 361 KB savings available
FIX
59 resources · 1.4 MB · 361 KB savings available
Warning::
Page weight 410 KB over 1MB target
Got: 1.4 MB Expected: ≤ 1 MB
Info::
~361 KB of savings available
Warning::
58 third-party resources (100% of weight)
Info::
1 resources over 200KB
59 resources · 1.4 MiB · 58 third-party 409.9 KiB over 1MB target
JavaScript 52% · 739.1 KiB
Image 22% · 316.9 KiB
Font 20% · 288.1 KiB
CSS 4% · 55.7 KiB
Document 2% · 31.3 KiB
Other 0% · 2.8 KiB

~360.9 KiB of savings available

Remove unused JavaScript: 360.9 KiB
F
HTTP Caching
Action
No cache headers
FIX
No cache headers
Warning::
No Cache-Control header found
Browsers will use heuristic caching, which can be unpredictable. Set explicit cache headers.

No Cache-Control header

Adding a Cache-Control header can significantly improve repeat-visit performance.

B
Page Weight Budget
1.4 MB transferred, 59 requests
REVIEW
1.4 MB transferred, 59 requests
Info::
Page weighs 3.4 MB (1.4 MB transferred)
Warning::
JavaScript is 739 KB — consider code splitting or lazy loading
Large JavaScript bundles delay interactivity. Split code by route or defer non-critical scripts.
Got: 739 KB
Info::
Fonts are 288 KB — consider subsetting or using system fonts
Subset fonts to include only used characters, or switch to system font stacks.
Got: 288 KB
Info::
59 HTTP requests
Info::
Estimated 0.29 g CO2 per page load
1.4 MB / 2.4 MB budget
1.4 MB transferred
59 requests
0.29 g CO2 per page load
JavaScript 739.1 KiB 52%
Images 314.2 KiB 22%
Fonts 288.1 KiB 20%
CSS 55.7 KiB 4%
HTML 31.3 KiB 2%
Other 2.9 KiB 0%
Other 1.6 KiB 0%
Other 556 B 0%
Other 450 B 0%
0 2.4 MB 4.9 MB
Under budget

Large JavaScript bundles delay interactivity. Split code by route or defer non-critical scripts.

Why this matters

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.

Why this matters

Font payload is large — subset to used glyphs only, or fall back to system fonts (zero load time).

Source: web.dev font loading

C
Green Hosting
Action
Whether the site is served from green-energy infrastructure
REVIEW

Green Hosting

No green hosting detected

A+
Text Compression
All text resources are compressed
PASS
All text resources are compressed
Info::
All text resources are compressed
All text resources are properly compressed.
A+
Image Optimization
6 images, 0 KB saveable
PASS
6 images, 0 KB saveable
Info::
All images are well-optimized
6 images 314 KB
0 oversized -0 KB
1 legacy format
0 missing dimensions CLS risk
A+
Font Loading
9 fonts (288 KB)
PASS
9 fonts (288 KB)
Info::
9 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

9

288 KB total

Render-blocking

0

of 9

Dominant font-display

swap

Most common across fonts

Font loading timeline
Transfer FOIT (block) FOUT (swap)
0 ms 2.0 s 4.0 s 6.0 s 8.0 s 10.0 s 12.0 s FCP 2.4 s LCP 11.8 shttps://www.nber.org/themes/custom/nber/assets/fonts/arimo-v17-latin_greek-regular.woff2arimo-v17-latin_greek-r... https://www.nber.org/themes/custom/nber/assets/fonts/arimo-v17-latin_greek-regular.woff2 — 16.4 KiB — 36 ms — font-display: swaphttps://www.nber.org/themes/custom/nber/assets/fonts/arimo-v17-latin_greek-700.woff2arimo-v17-latin_greek-7... https://www.nber.org/themes/custom/nber/assets/fonts/arimo-v17-latin_greek-700.woff2 — 16.4 KiB — 40 ms — font-display: swaphttps://www.nber.org/themes/custom/nber/assets/fonts/arimo-v17-latin_greek-italic.woff2arimo-v17-latin_greek-i... https://www.nber.org/themes/custom/nber/assets/fonts/arimo-v17-latin_greek-italic.woff2 — 18.2 KiB — 53 ms — font-display: swaphttps://www.nber.org/themes/custom/nber/assets/fonts/arimo-v17-latin_greek-700italic.woff2arimo-v17-latin_greek-7... https://www.nber.org/themes/custom/nber/assets/fonts/arimo-v17-latin_greek-700italic.woff2 — 18.2 KiB — 38 ms — font-display: swaphttps://www.nber.org/themes/custom/nber/assets/fonts/TiemposHeadlineWeb-Bold.woff2TiemposHeadlineWeb-Bold... https://www.nber.org/themes/custom/nber/assets/fonts/TiemposHeadlineWeb-Bold.woff2 — 40.6 KiB — 42 ms — font-display: swaphttps://www.nber.org/themes/custom/nber/assets/fonts/TiemposHeadlineWeb-Regular.woff2TiemposHeadlineWeb-Regu... https://www.nber.org/themes/custom/nber/assets/fonts/TiemposHeadlineWeb-Regular.woff2 — 41.9 KiB — 40 ms — font-display: swaphttps://www.nber.org/themes/custom/nber/assets/fonts/TiemposHeadlineWeb-Medium.woff2TiemposHeadlineWeb-Medi... https://www.nber.org/themes/custom/nber/assets/fonts/TiemposHeadlineWeb-Medium.woff2 — 40.6 KiB — 42 ms — font-display: swaphttps://www.nber.org/themes/custom/nber/assets/fonts/TiemposHeadlineWeb-Semibold.woff2TiemposHeadlineWeb-Semi... https://www.nber.org/themes/custom/nber/assets/fonts/TiemposHeadlineWeb-Semibold.woff2 — 40.2 KiB — 7 ms — font-display: swaphttps://www.nber.org/themes/custom/nber/assets/fonts/TiemposHeadlineWeb-Regular.woffTiemposHeadlineWeb-Regu... https://www.nber.org/themes/custom/nber/assets/fonts/TiemposHeadlineWeb-Regular.woff — 55.5 KiB — 11 ms — font-display: swap
arimo-v17-latin_greek-r... woff2 swap
Size 16 KB
Load time 36 ms
Start 257 ms
Risk FOUT — text flashes from fallback to web font
arimo-v17-latin_greek-7... woff2 swap
Size 16 KB
Load time 40 ms
Start 257 ms
Risk FOUT — text flashes from fallback to web font
arimo-v17-latin_greek-i... woff2 swap
Size 18 KB
Load time 53 ms
Start 257 ms
Risk FOUT — text flashes from fallback to web font
arimo-v17-latin_greek-7... woff2 swap
Size 18 KB
Load time 38 ms
Start 258 ms
Risk FOUT — text flashes from fallback to web font
TiemposHeadlineWeb-Bold... woff2 swap
Size 41 KB
Load time 42 ms
Start 258 ms
Risk FOUT — text flashes from fallback to web font
TiemposHeadlineWeb-Regu... woff2 swap
Size 42 KB
Load time 40 ms
Start 258 ms
Risk FOUT — text flashes from fallback to web font
TiemposHeadlineWeb-Medi... woff2 swap
Size 41 KB
Load time 42 ms
Start 259 ms
Risk FOUT — text flashes from fallback to web font
TiemposHeadlineWeb-Semi... woff2 swap
Size 40 KB
Load time 7 ms
Start 398 ms
Risk FOUT — text flashes from fallback to web font
TiemposHeadlineWeb-Regu... woff swap
Size 56 KB
Load time 11 ms
Start 399 ms
Risk FOUT — text flashes from fallback to web font
  • Convert to woff2 for ~30% smaller file size
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 ~17 KB and ~34 ms

A+
Resource Caching
All resources properly cached
PASS
All resources properly cached
Info::
No caching issues found
All static resources have appropriate caching headers.
A+
Critical Rendering Path
No render-blocking resources
PASS
No render-blocking resources
Info::
No render-blocking resources detected
A+
Resource Hints
9 hints, 0 missing preconnects
PASS
9 hints, 0 missing preconnects
Info::
Page uses 9 resource hint(s)

Current Resource Hints

preconnect
1
preload
8
dns-prefetch
—
prefetch
—

9 resource hints configured

A+
Render-Blocking Resources
No render-blocking resources detected
PASS
No render-blocking resources detected
Info::
No render-blocking resources detected in <head>
A+
Third-Party Resources
No third-party resources detected
PASS
No third-party resources detected
Network Waterfall
59 requests over 990ms
INFO
0 ms 2.0 s 4.0 s 6.0 s 8.0 s 10.0 s 12.0 s FCP 2.4 s LCP 11.8 shttps://nber.org// https://nber.org/ — 301 — 204 B — 15 ms — h2https://www.nber.org/www.nber.org/ https://www.nber.org/ — 200 — 31.3 KiB — 223 ms — h2https://www.nber.org/modules/custom/nber_user_auth/js/cookies.js?tduartwww.nber.org/modules/custom/nber_us... https://www.nber.org/modules/custom/nber_user_auth/js/cookies.js?tduart — 200 — 1.2 KiB — 19 ms — h2https://www.nber.org/sites/default/files/google_tag/primary/google_tag.script.js?tduartwww.nber.org/sites/default/files/go... https://www.nber.org/sites/default/files/google_tag/primary/google_tag.script.js?tduart — 200 — 633 B — 20 ms — h2https://www.nber.org/core/modules/system/css/components/align.module.css?tduartwww.nber.org/core/modules/system/cs... https://www.nber.org/core/modules/system/css/components/align.module.css?tduart — 200 — 580 B — 13 ms — h2https://www.nber.org/core/modules/system/css/components/fieldgroup.module.css?tduartwww.nber.org/core/modules/system/cs... https://www.nber.org/core/modules/system/css/components/fieldgroup.module.css?tduart — 200 — 425 B — 17 ms — h2https://www.nber.org/core/modules/system/css/components/container-inline.module.css?tduartwww.nber.org/core/modules/system/cs... https://www.nber.org/core/modules/system/css/components/container-inline.module.css?tduart — 200 — 434 B — 13 ms — h2https://www.nber.org/core/modules/system/css/components/clearfix.module.css?tduartwww.nber.org/core/modules/system/cs... https://www.nber.org/core/modules/system/css/components/clearfix.module.css?tduart — 200 — 522 B — 21 ms — h2https://www.nber.org/core/modules/system/css/components/details.module.css?tduartwww.nber.org/core/modules/system/cs... https://www.nber.org/core/modules/system/css/components/details.module.css?tduart — 200 — 404 B — 18 ms — h2https://www.nber.org/core/modules/system/css/components/hidden.module.css?tduartwww.nber.org/core/modules/system/cs... https://www.nber.org/core/modules/system/css/components/hidden.module.css?tduart — 200 — 940 B — 13 ms — h2https://www.nber.org/core/modules/system/css/components/item-list.module.css?tduartwww.nber.org/core/modules/system/cs... https://www.nber.org/core/modules/system/css/components/item-list.module.css?tduart — 200 — 387 B — 14 ms — h2https://www.nber.org/core/modules/system/css/components/js.module.css?tduartwww.nber.org/core/modules/system/cs... https://www.nber.org/core/modules/system/css/components/js.module.css?tduart — 200 — 606 B — 22 ms — h2https://www.nber.org/core/modules/system/css/components/nowrap.module.css?tduartwww.nber.org/core/modules/system/cs... https://www.nber.org/core/modules/system/css/components/nowrap.module.css?tduart — 200 — 425 B — 22 ms — h2https://www.nber.org/core/modules/system/css/components/position-container.module.css?tduartwww.nber.org/core/modules/system/cs... https://www.nber.org/core/modules/system/css/components/position-container.module.css?tduart — 200 — 442 B — 27 ms — h2https://www.nber.org/core/modules/system/css/components/reset-appearance.module.css?tduartwww.nber.org/core/modules/system/cs... https://www.nber.org/core/modules/system/css/components/reset-appearance.module.css?tduart — 200 — 470 B — 22 ms — h2https://www.nber.org/core/modules/system/css/components/resize.module.css?tduartwww.nber.org/core/modules/system/cs... https://www.nber.org/core/modules/system/css/components/resize.module.css?tduart — 200 — 417 B — 24 ms — h2https://www.nber.org/core/modules/system/css/components/system-status-counter.css?tduartwww.nber.org/core/modules/system/cs... https://www.nber.org/core/modules/system/css/components/system-status-counter.css?tduart — 200 — 536 B — 23 ms — h2https://www.nber.org/core/modules/system/css/components/system-status-report-counters.css?tduartwww.nber.org/core/modules/system/cs... https://www.nber.org/core/modules/system/css/components/system-status-report-counters.css?tduart — 200 — 593 B — 27 ms — h2https://www.nber.org/core/modules/system/css/components/system-status-report-general-info.css?tduartwww.nber.org/core/modules/system/cs... https://www.nber.org/core/modules/system/css/components/system-status-report-general-info.css?tduart — 200 — 432 B — 27 ms — h2https://www.nber.org/core/modules/system/css/components/tablesort.module.css?tduartwww.nber.org/core/modules/system/cs... https://www.nber.org/core/modules/system/css/components/tablesort.module.css?tduart — 200 — 483 B — 28 ms — h2https://www.nber.org/core/modules/views/css/views.module.css?tduartwww.nber.org/core/modules/views/css... https://www.nber.org/core/modules/views/css/views.module.css?tduart — 200 — 521 B — 28 ms — h2https://www.nber.org/modules/custom/nber_charts/css/unemployment-graphic.css?tduartwww.nber.org/modules/custom/nber_ch... https://www.nber.org/modules/custom/nber_charts/css/unemployment-graphic.css?tduart — 200 — 521 B — 23 ms — h2https://www.nber.org/modules/contrib/paragraphs/css/paragraphs.unpublished.css?tduartwww.nber.org/modules/contrib/paragr... https://www.nber.org/modules/contrib/paragraphs/css/paragraphs.unpublished.css?tduart — 200 — 331 B — 29 ms — h2https://www.nber.org/modules/contrib/sitewide_alert/css/sitewide_alert.css?tduartwww.nber.org/modules/contrib/sitewi... https://www.nber.org/modules/contrib/sitewide_alert/css/sitewide_alert.css?tduart — 200 — 439 B — 31 ms — h2https://www.nber.org/themes/custom/nber/assets/build/css/nber-generated.css?tduartwww.nber.org/themes/custom/nber/ass... https://www.nber.org/themes/custom/nber/assets/build/css/nber-generated.css?tduart — 200 — 46.0 KiB — 44 ms — h2https://www.nber.org/themes/custom/nber/assets/fonts/arimo-v17-latin_greek-regular.woff2www.nber.org/themes/custom/nber/ass... https://www.nber.org/themes/custom/nber/assets/fonts/arimo-v17-latin_greek-regular.woff2 — 200 — 16.4 KiB — 36 ms — h2https://www.nber.org/themes/custom/nber/assets/fonts/arimo-v17-latin_greek-700.woff2www.nber.org/themes/custom/nber/ass... https://www.nber.org/themes/custom/nber/assets/fonts/arimo-v17-latin_greek-700.woff2 — 200 — 16.4 KiB — 40 ms — h2https://www.nber.org/themes/custom/nber/assets/fonts/arimo-v17-latin_greek-italic.woff2www.nber.org/themes/custom/nber/ass... https://www.nber.org/themes/custom/nber/assets/fonts/arimo-v17-latin_greek-italic.woff2 — 200 — 18.2 KiB — 53 ms — h2https://www.nber.org/themes/custom/nber/assets/fonts/arimo-v17-latin_greek-700italic.woff2www.nber.org/themes/custom/nber/ass... https://www.nber.org/themes/custom/nber/assets/fonts/arimo-v17-latin_greek-700italic.woff2 — 200 — 18.2 KiB — 38 ms — h2https://www.nber.org/themes/custom/nber/assets/fonts/TiemposHeadlineWeb-Bold.woff2www.nber.org/themes/custom/nber/ass... https://www.nber.org/themes/custom/nber/assets/fonts/TiemposHeadlineWeb-Bold.woff2 — 200 — 40.6 KiB — 42 ms — h2
0 ms 2.0 s 4.0 s 6.0 s 8.0 s 10.0 s 12.0 s FCP 2.4 s LCP 11.8 shttps://nber.org// https://nber.org/ — 301 — 204 B — 15 ms — h2https://www.nber.org/www.nber.org/ https://www.nber.org/ — 200 — 31.3 KiB — 223 ms — h2https://www.nber.org/modules/custom/nber_user_auth/js/cookies.js?tduartwww.nber.org/modules/custom/nber_us... https://www.nber.org/modules/custom/nber_user_auth/js/cookies.js?tduart — 200 — 1.2 KiB — 19 ms — h2https://www.nber.org/sites/default/files/google_tag/primary/google_tag.script.js?tduartwww.nber.org/sites/default/files/go... https://www.nber.org/sites/default/files/google_tag/primary/google_tag.script.js?tduart — 200 — 633 B — 20 ms — h2https://www.nber.org/core/modules/system/css/components/align.module.css?tduartwww.nber.org/core/modules/system/cs... https://www.nber.org/core/modules/system/css/components/align.module.css?tduart — 200 — 580 B — 13 ms — h2https://www.nber.org/core/modules/system/css/components/fieldgroup.module.css?tduartwww.nber.org/core/modules/system/cs... https://www.nber.org/core/modules/system/css/components/fieldgroup.module.css?tduart — 200 — 425 B — 17 ms — h2https://www.nber.org/core/modules/system/css/components/container-inline.module.css?tduartwww.nber.org/core/modules/system/cs... https://www.nber.org/core/modules/system/css/components/container-inline.module.css?tduart — 200 — 434 B — 13 ms — h2https://www.nber.org/core/modules/system/css/components/clearfix.module.css?tduartwww.nber.org/core/modules/system/cs... https://www.nber.org/core/modules/system/css/components/clearfix.module.css?tduart — 200 — 522 B — 21 ms — h2https://www.nber.org/core/modules/system/css/components/details.module.css?tduartwww.nber.org/core/modules/system/cs... https://www.nber.org/core/modules/system/css/components/details.module.css?tduart — 200 — 404 B — 18 ms — 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HTML JavaScript CSS Images Fonts XHR/Fetch Other
Third-Party Script Cost
Per-script blocking time, transfer cost, and cache headers
INFO
100% of JavaScript execution is third-party
First-party Third-party 2450ms · 751KB · $33/mo
www.nber.org
Other
Costly
Execution 690ms
Transfer 31 KB
Monthly Cost $9/mo
cdnjs
CDN
Costly
Execution 468ms
Transfer 73 KB
Unused 75%
Monthly Cost $6/mo
www.nber.org
Other
Costly
Execution 300ms
Transfer 51 KB
Unused 64%
Monthly Cost $4/mo
Unattributable
Other
Costly
Execution 277ms
Transfer 0 KB
Monthly Cost $4/mo
Google Tag Manager
Tag Manager
Costly
Execution 249ms
Transfer 144 KB
Unused 44%
Monthly Cost $3/mo
Google Tag Manager
Tag Manager
Costly
Execution 235ms
Transfer 156 KB
Unused 41%
Monthly Cost $3/mo
www.nber.org
Other
Optional
Execution 114ms
Transfer 273 KB
Unused 54%
Monthly Cost $2/mo
www.nber.org
Other
Optional
Execution 61ms
Transfer 2 KB
Monthly Cost $1/mo
Google Analytics
Analytics
Optional
Execution 55ms
Transfer 21 KB
Monthly Cost $1/mo

These scripts may cost more than they're worth

  • www.nber.org adds 690ms and costs ~$9/month
  • cdnjs adds 468ms and costs ~$6/month
  • www.nber.org adds 300ms and costs ~$4/month
  • Unattributable adds 277ms and costs ~$4/month
  • Google Tag Manager adds 249ms and costs ~$3/month
  • Google Tag Manager adds 235ms and costs ~$3/month

100% of JavaScript execution time is spent on third-party scripts. Consider auditing which scripts are essential.

Why this matters

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.nber.org takes 690ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.

Why this matters

This script has high main-thread execution time — optimize hot paths or defer.

Source: web.dev

cdnjs takes 468ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.

Why this matters

This script has high main-thread execution time — optimize hot paths or defer.

Source: web.dev

75% of cdnjs's code is unused. The script may be loading features you don't use.

Why this matters

Bundle has high unused-code ratio — tree-shaking and route-splitting recover the wasted bytes.

Source: web.dev

www.nber.org takes 300ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.

Why this matters

This script has high main-thread execution time — optimize hot paths or defer.

Source: web.dev

64% of www.nber.org's code is unused. The script may be loading features you don't use.

Why this matters

Bundle has high unused-code ratio — tree-shaking and route-splitting recover the wasted bytes.

Source: web.dev

Unattributable takes 277ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.

Why this matters

This script has high main-thread execution time — optimize hot paths or defer.

Source: web.dev

Google Tag Manager takes 249ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.

Why this matters

This script has high main-thread execution time — optimize hot paths or defer.

Source: web.dev

Google Tag Manager takes 235ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.

Why this matters

This script has high main-thread execution time — optimize hot paths or defer.

Source: web.dev

54% of www.nber.org's code is unused. The script may be loading features you don't use.

Why this matters

Bundle has high unused-code ratio — tree-shaking and route-splitting recover the wasted bytes.

Source: web.dev

How third-party costs are calculated

All checks on this page are automated. Results are estimates - run targeted manual reviews when the score affects a release decision.

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