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Performance

· 15 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
83
GRADE
B
FIX
1
REVIEW
4
PASS
8
INFO
2

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

Mobile Desktop
99
Performance Overall performance score (0–100) based on Core Web Vitals and other metrics. 90+ is good.
100
Accessibility Measures how accessible the page is for users with disabilities. Checks color contrast, ARIA labels, and semantic HTML.
100
Best Practices Checks for modern web development best practices including HTTPS, no console errors, and secure JavaScript.
92
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.

628 ms

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

778 ms

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

2 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.

718 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.

1.58 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
15
8 PASS 4 REVIEW 1 FIX
D
Third-Party Impact
Action
99% third-party, 0 ms blocking
FIX
99% third-party, 0 ms blocking
Warning::
Third-party code accounts for 99% of page weight (804.6 KiB of 816.4 KiB)
Info::
Third-party blocking time is low (0 ms)
99%
First-party Third-party
C
Image Optimization
Action
14 images, 0 KB saveable
REVIEW
14 images, 0 KB saveable
Warning::
https://cdn.ncbi.nlm.nih.gov/coreutils/uswds/img/f... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://cdn.ncbi.nlm.nih.gov/coreutils/nwds/img/lo... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://cdn.ncbi.nlm.nih.gov/pubmed/ffd2ec78-62e5-... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
14 images 24 KB
0 oversized -0 KB
12 legacy format
3 missing dimensions CLS risk

Set explicit width and height to prevent CLS.

Why this matters

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.

Why this matters

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.

Why this matters

Image without explicit width/height — browser can't reserve space; CLS jumps when image loads.

Source: web.dev / Core Web Vitals

C
JS Bundles
Action
17 scripts, 251 KB unused
REVIEW
17 scripts, 251 KB unused
Warning::
https://www.googletagmanager.com/gtag/js?id=G-CSLL...: 62 KB unused (42%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.googletagmanager.com/gtag/js?id=G-DP2X...: 62 KB unused (42%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.googletagmanager.com/gtm.js?id=GTM-PC9...: 60 KB unused (47%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://siteintercept.qualtrics.com/dxjsmodule/12....: 22 KB unused (63%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://cdn.ncbi.nlm.nih.gov/pubmed/ffd2ec78-62e5-...: 22 KB unused (43%)
Consider code splitting or tree shaking to reduce unused code.
Info::
Total unused JavaScript: 251 KB
251 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://www.googletagmanager.com/gtag/js?id=G-CSLL4ZEK4L147 KB62 KB (42%)✓3rd
https://www.googletagmanager.com/gtag/js?id=G-DP2X732JSX&l=pingerDataLayer&cx=c&gtm=4e64h1148 KB62 KB (42%)✓3rd
https://www.googletagmanager.com/gtm.js?id=GTM-PC9B6M3&l=pingerDataLayer130 KB60 KB (47%)✓3rd
https://siteintercept.qualtrics.com/dxjsmodule/12.1a2b7192fd54e87d3971.chunk.js?Q_CLIENTVERSION=2.46.0&Q_CLIENTTYPE=web&Q_BRANDID=pubmed.ncbi.nlm.nih.gov36 KB22 KB (63%)✓3rd
https://cdn.ncbi.nlm.nih.gov/pubmed/ffd2ec78-62e5-42af-9cba-3b683627d12e/CACHE/js/output.1119c5b65e07.js52 KB22 KB (43%)✓3rd
https://siteintercept.qualtrics.com/dxjsmodule/CoreModule.js?Q_CLIENTVERSION=2.46.0&Q_CLIENTTYPE=web&Q_BRANDID=nlmenterprise31 KB22 KB (71%)✓3rd
https://dap.digitalgov.gov/Universal-Federated-Analytics-Min.js?agency=HHS&subagency=NCBI%20-%20ncbi.nlm.nih.gov&sitetopic=NCBI%20Pinger%200.39.3&siteplatform=NCBI%20Pinger%200.39.39 KB—✓3rd
https://cdn.ncbi.nlm.nih.gov/core/alerts/alerts.js?_=17767972507646 KB—✓3rd
https://cdn.ncbi.nlm.nih.gov/pubmed/ffd2ec78-62e5-42af-9cba-3b683627d12e/core/dismissable-ncbi-alert.js2 KB—✓3rd
https://dap.digitalgov.gov/web-vitals/dist/web-vitals.attribution.iife.js4 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

B
Page Weight Inventory
44 resources · 816 KB · 251 KB savings available
REVIEW
44 resources · 816 KB · 251 KB savings available
Info::
Within 1MB page-weight target
Got: 816 KB
Info::
~251 KB of savings available
Warning::
41 third-party resources (99% of weight)
44 resources · 816.4 KiB · 41 third-party Within 1MB page-weight target
JavaScript 84% · 681.8 KiB
Image 7% · 58.9 KiB
CSS 4% · 31.0 KiB
Font 3% · 26.4 KiB
Document 1% · 11.5 KiB
Other 1% · 6.8 KiB

~251.4 KiB of savings available

Remove unused JavaScript: 251.4 KiB
B
HTTP Caching
private
REVIEW
private
Info::
Cache-Control header is set
Got: private
Info::
No ETag or Last-Modified header
Conditional requests (304 Not Modified) are not possible without validators.
Cache-Control

private

DirectiveValueMeaning
private—Only browser cache, not CDN/proxy
A
Page Weight Budget
816 KB transferred, 44 requests
PASS
816 KB transferred, 44 requests
Info::
Page weighs 2.4 MB (816 KB transferred)
Warning::
JavaScript is 682 KB — consider code splitting or lazy loading
Large JavaScript bundles delay interactivity. Split code by route or defer non-critical scripts.
Got: 682 KB
Info::
44 HTTP requests
Info::
Estimated 0.17 g CO2 per page load
816 KB / 2.4 MB budget
816 KB transferred
44 requests
0.17 g CO2 per page load
JavaScript 681.8 KiB 84%
Other 35.4 KiB 4%
CSS 31.0 KiB 4%
Fonts 26.4 KiB 3%
Images 23.5 KiB 3%
HTML 11.5 KiB 1%
Other 6.1 KiB 1%
Other 691 B 0%
Other 0 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

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+
JS Execution Cost
456ms total JS execution
PASS
456ms total JS execution
Info::
Unattributable: 105ms CPU time
Info::
https://pubmed.ncbi.nlm.nih.gov/: 100ms CPU time
Info::
https://siteintercept.qualtrics.com/dxjsmodule/12....: 72ms CPU time
Info::
https://www.googletagmanager.com/gtm.js?id=GTM-PC9...: 64ms CPU time
Info::
https://www.googletagmanager.com/gtag/js?id=G-CSLL...: 61ms CPU time
Warning::
Third-party scripts: 356ms (78% of total)

Main Thread Breakdown

Script Evaluation 53% Other 20% Style & Layout 11% Script Parsing & Compilation 9%
ScriptTotalScriptingParse/CompileParty
Unattributable105ms4ms0ms3rd
https://pubmed.ncbi.nlm.nih.gov/100ms16ms1ms1st
https://siteintercept.qualtrics.com/dxjsmodule/12.1a2b7192fd54e87d3971.chunk.js?Q_CLIENTVERSION=2.46.0&Q_CLIENTTYPE=web&Q_BRANDID=pubmed.ncbi.nlm.nih.gov72ms64ms3ms3rd
https://www.googletagmanager.com/gtm.js?id=GTM-PC9B6M3&l=pingerDataLayer64ms50ms11ms3rd
https://www.googletagmanager.com/gtag/js?id=G-CSLL4ZEK4L61ms48ms10ms3rd
https://www.googletagmanager.com/gtag/js?id=G-DP2X732JSX&l=pingerDataLayer&cx=c&gtm=4e64h154ms43ms9ms3rd
A+
Font Loading
1 fonts (26 KB)
PASS
1 fonts (26 KB)
Info::
1 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

1

26 KB total

Render-blocking

0

of 1

Dominant font-display

swap

Most common across fonts

Font loading timeline
Transfer FOIT (block) FOUT (swap)
0 ms 500 ms 1.0 s FCP 628 ms LCP 778 mshttps://cdn.ncbi.nlm.nih.gov/pubmed/ffd2ec78-62e5-42af-9cba-3b683627d12e/uswds/dist/fonts/merriweather-bold-webfont.woff2merriweather-bold-webfo... https://cdn.ncbi.nlm.nih.gov/pubmed/ffd2ec78-62e5-42af-9cba-3b683627d12e/uswds/dist/fonts/merriweather-bold-webfont.woff2 — 26.4 KiB — 55 ms — font-display: swap
merriweather-bold-webfo... woff2 swap
Size 26 KB
Load time 55 ms
Start 350 ms
Risk FOUT — text flashes from fallback to web font
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)
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
No optimization needed
PASS
No optimization needed
Info::
No resource hint issues
A+
Green Hosting
Whether the site is served from green-energy infrastructure
PASS

Green Hosting

This site is hosted on green energy infrastructure

Provider: Google Cloud

Network Waterfall
44 requests over 1139ms
INFO
0 ms 500 ms 1.0 s FCP 628 ms LCP 778 mshttps://pubmed.ncbi.nlm.nih.gov// https://pubmed.ncbi.nlm.nih.gov/ — 200 — 11.5 KiB — 185 ms — h2https://cdn.ncbi.nlm.nih.gov/pubmed/ffd2ec78-62e5-42af-9cba-3b683627d12e/CACHE/css/output.8af684516550.csscdn.ncbi.nlm.nih.gov/pubmed/ffd2ec7... https://cdn.ncbi.nlm.nih.gov/pubmed/ffd2ec78-62e5-42af-9cba-3b683627d12e/CACHE/css/output.8af684516550.css — 200 — 18.6 KiB — 74 ms — h2https://cdn.ncbi.nlm.nih.gov/pubmed/ffd2ec78-62e5-42af-9cba-3b683627d12e/CACHE/css/output.452c70ce66f7.csscdn.ncbi.nlm.nih.gov/pubmed/ffd2ec7... https://cdn.ncbi.nlm.nih.gov/pubmed/ffd2ec78-62e5-42af-9cba-3b683627d12e/CACHE/css/output.452c70ce66f7.css — 200 — 2.6 KiB — 62 ms — h2https://cdn.ncbi.nlm.nih.gov/pubmed/ffd2ec78-62e5-42af-9cba-3b683627d12e/CACHE/css/output.c71ac2b2c597.csscdn.ncbi.nlm.nih.gov/pubmed/ffd2ec7... https://cdn.ncbi.nlm.nih.gov/pubmed/ffd2ec78-62e5-42af-9cba-3b683627d12e/CACHE/css/output.c71ac2b2c597.css — 200 — 5.7 KiB — 79 ms — h2https://cdn.ncbi.nlm.nih.gov/pubmed/ffd2ec78-62e5-42af-9cba-3b683627d12e/CACHE/css/output.2456e20ee0f0.csscdn.ncbi.nlm.nih.gov/pubmed/ffd2ec7... https://cdn.ncbi.nlm.nih.gov/pubmed/ffd2ec78-62e5-42af-9cba-3b683627d12e/CACHE/css/output.2456e20ee0f0.css — 200 — 4.2 KiB — 78 ms — h2https://cdn.ncbi.nlm.nih.gov/coreutils/uswds/img/favicons/favicon-57.pngcdn.ncbi.nlm.nih.gov/coreutils/uswd... https://cdn.ncbi.nlm.nih.gov/coreutils/uswds/img/favicons/favicon-57.png — 200 — 909 B — 78 ms — h2https://cdn.ncbi.nlm.nih.gov/coreutils/uswds/img/icon-dot-gov.svgcdn.ncbi.nlm.nih.gov/coreutils/uswd... https://cdn.ncbi.nlm.nih.gov/coreutils/uswds/img/icon-dot-gov.svg — 200 — 943 B — 78 ms — h2https://cdn.ncbi.nlm.nih.gov/coreutils/uswds/img/icon-https.svgcdn.ncbi.nlm.nih.gov/coreutils/uswd... https://cdn.ncbi.nlm.nih.gov/coreutils/uswds/img/icon-https.svg — 200 — 791 B — 23 ms — h2https://cdn.ncbi.nlm.nih.gov/coreutils/nwds/img/logos/AgencyLogo.svgcdn.ncbi.nlm.nih.gov/coreutils/nwds... https://cdn.ncbi.nlm.nih.gov/coreutils/nwds/img/logos/AgencyLogo.svg — 200 — 8.8 KiB — 25 ms — h2https://cdn.ncbi.nlm.nih.gov/pubmed/ffd2ec78-62e5-42af-9cba-3b683627d12e/core/images/pubmed-logo-white.svgcdn.ncbi.nlm.nih.gov/pubmed/ffd2ec7... https://cdn.ncbi.nlm.nih.gov/pubmed/ffd2ec78-62e5-42af-9cba-3b683627d12e/core/images/pubmed-logo-white.svg — 200 — 1.9 KiB — 27 ms — h2https://cdn.ncbi.nlm.nih.gov/pubmed/ffd2ec78-62e5-42af-9cba-3b683627d12e/CACHE/js/output.1119c5b65e07.jscdn.ncbi.nlm.nih.gov/pubmed/ffd2ec7... https://cdn.ncbi.nlm.nih.gov/pubmed/ffd2ec78-62e5-42af-9cba-3b683627d12e/CACHE/js/output.1119c5b65e07.js — 200 — 51.9 KiB — 46 ms — h2https://cdn.ncbi.nlm.nih.gov/pubmed/ffd2ec78-62e5-42af-9cba-3b683627d12e/CACHE/js/output.598ebf77bf13.jscdn.ncbi.nlm.nih.gov/pubmed/ffd2ec7... https://cdn.ncbi.nlm.nih.gov/pubmed/ffd2ec78-62e5-42af-9cba-3b683627d12e/CACHE/js/output.598ebf77bf13.js — 200 — 26.4 KiB — 41 ms — h2https://cdn.ncbi.nlm.nih.gov/pubmed/ffd2ec78-62e5-42af-9cba-3b683627d12e/CACHE/js/output.a84df1e17580.jscdn.ncbi.nlm.nih.gov/pubmed/ffd2ec7... https://cdn.ncbi.nlm.nih.gov/pubmed/ffd2ec78-62e5-42af-9cba-3b683627d12e/CACHE/js/output.a84df1e17580.js — 200 — 29.7 KiB — 52 ms — h2https://cdn.ncbi.nlm.nih.gov/core/pinger/pinger.jscdn.ncbi.nlm.nih.gov/core/pinger/pi... https://cdn.ncbi.nlm.nih.gov/core/pinger/pinger.js — 200 — 29.4 KiB — 56 ms — h2data:image/svg+xml;base64,PHN2ZyB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciIHdpZHRoPSI1MTIiIGhla…data:image/svg+xml;base64,PHN2ZyB4b... data:image/svg+xml;base64,PHN2ZyB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciIHdpZHRoPSI1MTIiIGhla… — 200 — 0 B — 0 ms — datadata:image/svg+xml;base64,PHN2ZyB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciIHZpZXdCb3g9IjAgMCA0O…data:image/svg+xml;base64,PHN2ZyB4b... data:image/svg+xml;base64,PHN2ZyB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciIHZpZXdCb3g9IjAgMCA0O… — 200 — 0 B — 0 ms — datahttps://cdn.ncbi.nlm.nih.gov/pubmed/ffd2ec78-62e5-42af-9cba-3b683627d12e/core/images/homepage-background.svgcdn.ncbi.nlm.nih.gov/pubmed/ffd2ec7... https://cdn.ncbi.nlm.nih.gov/pubmed/ffd2ec78-62e5-42af-9cba-3b683627d12e/core/images/homepage-background.svg — 200 — 6.6 KiB — 33 ms — h3https://cdn.ncbi.nlm.nih.gov/pubmed/ffd2ec78-62e5-42af-9cba-3b683627d12e/core/images/learn.svgcdn.ncbi.nlm.nih.gov/pubmed/ffd2ec7... https://cdn.ncbi.nlm.nih.gov/pubmed/ffd2ec78-62e5-42af-9cba-3b683627d12e/core/images/learn.svg — 200 — 1.0 KiB — 29 ms — h3https://cdn.ncbi.nlm.nih.gov/pubmed/ffd2ec78-62e5-42af-9cba-3b683627d12e/core/images/find.svgcdn.ncbi.nlm.nih.gov/pubmed/ffd2ec7... https://cdn.ncbi.nlm.nih.gov/pubmed/ffd2ec78-62e5-42af-9cba-3b683627d12e/core/images/find.svg — 200 — 866 B — 32 ms — h3https://cdn.ncbi.nlm.nih.gov/pubmed/ffd2ec78-62e5-42af-9cba-3b683627d12e/core/images/download-home-illustration.svgcdn.ncbi.nlm.nih.gov/pubmed/ffd2ec7... https://cdn.ncbi.nlm.nih.gov/pubmed/ffd2ec78-62e5-42af-9cba-3b683627d12e/core/images/download-home-illustration.svg — 200 — 607 B — 32 ms — h3https://cdn.ncbi.nlm.nih.gov/pubmed/ffd2ec78-62e5-42af-9cba-3b683627d12e/core/images/explore.svgcdn.ncbi.nlm.nih.gov/pubmed/ffd2ec7... https://cdn.ncbi.nlm.nih.gov/pubmed/ffd2ec78-62e5-42af-9cba-3b683627d12e/core/images/explore.svg — 200 — 849 B — 33 ms — h3https://cdn.ncbi.nlm.nih.gov/pubmed/ffd2ec78-62e5-42af-9cba-3b683627d12e/uswds/dist/fonts/merriweather-bold-webfont.woff2cdn.ncbi.nlm.nih.gov/pubmed/ffd2ec7... https://cdn.ncbi.nlm.nih.gov/pubmed/ffd2ec78-62e5-42af-9cba-3b683627d12e/uswds/dist/fonts/merriweather-bold-webfont.woff2 — 200 — 26.4 KiB — 55 ms — h3https://cdn.ncbi.nlm.nih.gov/pubmed/ffd2ec78-62e5-42af-9cba-3b683627d12e/core/dismissable-ncbi-alert.jscdn.ncbi.nlm.nih.gov/pubmed/ffd2ec7... https://cdn.ncbi.nlm.nih.gov/pubmed/ffd2ec78-62e5-42af-9cba-3b683627d12e/core/dismissable-ncbi-alert.js — 200 — 1.5 KiB — 21 ms — h3https://cdn.ncbi.nlm.nih.gov/core/alerts/alerts.js?_=1776797250764cdn.ncbi.nlm.nih.gov/core/alerts/al... https://cdn.ncbi.nlm.nih.gov/core/alerts/alerts.js?_=1776797250764 — 200 — 5.9 KiB — 24 ms — h3https://www.googletagmanager.com/gtm.js?id=GTM-PC9B6M3&l=pingerDataLayerwww.googletagmanager.com/gtm.js?id=... https://www.googletagmanager.com/gtm.js?id=GTM-PC9B6M3&l=pingerDataLayer — 200 — 129.9 KiB — 138 ms — h2https://pubmed.ncbi.nlm.nih.gov/stat?HTTP_REFERER=&SELF_URL=https%3A%2F%2Fpubmed.ncbi.nlm.nih.gov%2F&browserheight=940&browserwidth=1350&colorDepth=24&connection_effectivetype=4g&connection_type=&cookieSize=0&cookieenabled=true&is_browser_supported=true&jsevent=render&jsloadtime=&jsperf_basePage=4&jsperf_connect=38&jsperf_dns=0&jsperf_navTimingNetworkMS=187&jsperf_navTimingRedirectCount=0&jsperf_navTimingType=navigate&jsperf_navType=0&jsperf_redirectCount=0&jsperf_ttfb=144&jsrendertime=&language_code=en-US&log_category=literature&log_op=page_view&myncbi_signed_in=false&ncbi_algorithm=&ncbi_app=pubmed&ncbi_cost_center=pubmed&ncbi_db=pubmed&ncbi_featured_srcdb=&ncbi_nwds=yes&ncbi_nwds_ver=1.2.5&ncbi_pcid=&ncbi_pdid=home&ncbi_phid=399000018CBD6D35000039E9B8151D9A.1.m_1&ncbi_program=&ncbi_timesinceload=5&ncbi_timesincenavstart=458&pagename=pubmed%3Apubmed%3Ahome%3ANONE&pinger_in_iframe=false&screenavailheight=600&screenavailwidth=800&screenheight=600&screenwidth=800&server=pubmed.ncbi.nlm.nih.gov&sgSource=native&sgversion=0.42.0&sgversion_hotfix=0&sgversion_major=0&sgversion_minor=42&spa_index=0/stat?HTTP_REFERER=&SELF_URL=https%... 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https://region1.google-analytics.com/g/collect?v=2&tid=G-CSLL4ZEK4L&gtm=45je64h1h1v9131934939za200zd9131934939&_p=1776797251095&gcd=13l3lPl2l1l1&npa=1&dma_cps=a&dma=1&are=1&cid=1052100452.1776797251&frm=0&pscdl=noapi&rcb=7&sr=800x600&uaa=x86&uab=64&uafvl=Chromium%3B147.0.7727.101%7CNot.A%252FBrand%3B8.0.0.0&uam=&uamb=0&uap=macOS&uapv=10.15.7&uaw=0&ul=en-us&_s=1&tag_exp=0~115938466~115938469~117266400~118463262&dl=https%3A%2F%2Fpubmed.ncbi.nlm.nih.gov%2F&dt=PubMed&dr=&sid=1776797251&sct=1&seg=0&_tu=wA&en=page_view&_fv=1&_ss=1&_ee=1&ep.agency=HHS&ep.subagency=NCBI%20-%20NCBI.NLM.NIH.GOV&ep.site_topic=ncbi%20pinger%200.39.3&ep.site_platform=ncbi%20pinger%200.39.3&ep.script_source=https%3A%2F%2Fdap.digitalgov.gov%2Funiversal-federated-analytics-min.js&ep.version=20250702%20v8.7%20-%20ga4&ep.protocol=https%3A&ep.using_parallel_tracker=no&ep.hostname_dimension=pubmed.ncbi.nlm.nih.gov&tfd=838 — 204 — 48 B — 25 ms — h2https://zndikywqsjiuwn0q5-nlmenterprise.siteintercept.qualtrics.com/SIE/?Q_ZID=ZN_dikYWqsjiUWN0Q5zndikywqsjiuwn0q5-nlmenterprise.sit... https://zndikywqsjiuwn0q5-nlmenterprise.siteintercept.qualtrics.com/SIE/?Q_ZID=ZN_dikYWqsjiUWN0Q5 — 200 — 4.6 KiB — 66 ms — h2https://cdn.ncbi.nlm.nih.gov/coreutils/nwds/img/favicons/favicon.pngcdn.ncbi.nlm.nih.gov/coreutils/nwds... https://cdn.ncbi.nlm.nih.gov/coreutils/nwds/img/favicons/favicon.png — 200 — 1.7 KiB — 22 ms — h3https://cdn.ncbi.nlm.nih.gov/coreutils/nwds/img/favicons/favicon.icocdn.ncbi.nlm.nih.gov/coreutils/nwds... https://cdn.ncbi.nlm.nih.gov/coreutils/nwds/img/favicons/favicon.ico — 200 — 33.7 KiB — 32 ms — h3https://siteintercept.qualtrics.com/dxjsmodule/37.7ea1ffe71ad8c0799cc1.chunk.js?Q_CLIENTVERSION=2.46.0&Q_CLIENTTYPE=web&Q_BRANDID=pubmed.ncbi.nlm.nih.govsiteintercept.qualtrics.com/dxjsmod... 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h2https://siteintercept.qualtrics.com/dxjsmodule/CoreModule.js?Q_CLIENTVERSION=2.46.0&Q_CLIENTTYPE=web&Q_BRANDID=nlmenterprisesiteintercept.qualtrics.com/dxjsmod... https://siteintercept.qualtrics.com/dxjsmodule/CoreModule.js?Q_CLIENTVERSION=2.46.0&Q_CLIENTTYPE=web&Q_BRANDID=nlmenterprise — 200 — 30.9 KiB — 27 ms — h2https://siteintercept.qualtrics.com/dxjsmodule/7.f7df015b06d8a90ce822.chunk.js?Q_CLIENTVERSION=2.46.0&Q_CLIENTTYPE=web&Q_BRANDID=nlmenterprisesiteintercept.qualtrics.com/dxjsmod... https://siteintercept.qualtrics.com/dxjsmodule/7.f7df015b06d8a90ce822.chunk.js?Q_CLIENTVERSION=2.46.0&Q_CLIENTTYPE=web&Q_BRANDID=nlmenterprise — 200 — 1.4 KiB — 26 ms — h2https://siteintercept.qualtrics.com/dxjsmodule/1.bc67e778235741631577.chunk.js?Q_CLIENTVERSION=2.46.0&Q_CLIENTTYPE=web&Q_BRANDID=nlmenterprisesiteintercept.qualtrics.com/dxjsmod... https://siteintercept.qualtrics.com/dxjsmodule/1.bc67e778235741631577.chunk.js?Q_CLIENTVERSION=2.46.0&Q_CLIENTTYPE=web&Q_BRANDID=nlmenterprise — 200 — 7.1 KiB — 25 ms — h2
HTML JavaScript CSS Images Fonts XHR/Fetch Other
Third-Party Script Cost
Per-script blocking time, transfer cost, and cache headers
INFO
78% of JavaScript execution is third-party
First-party Third-party 356ms · 460KB · $5/mo
Unattributable
Other
Optional
Execution 105ms
Transfer 0 KB
Monthly Cost $1/mo
siteintercept.qualtrics.com
Other
Optional
Execution 72ms
Transfer 36 KB
Unused 63%
Monthly Cost $1/mo
Google Tag Manager
Tag Manager
Optional
Execution 64ms
Transfer 130 KB
Unused 47%
Monthly Cost $1/mo
Google Tag Manager
Tag Manager
Optional
Execution 61ms
Transfer 147 KB
Unused 42%
Monthly Cost $1/mo
Google Tag Manager
Tag Manager
Optional
Execution 54ms
Transfer 148 KB
Unused 42%
Monthly Cost $1/mo

78% 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

63% of siteintercept.qualtrics.com'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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