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https://osti.gov

Performance

· 15 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
87
GRADE
B
FIX
2
REVIEW
3
PASS
8
INFO
2

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

Mobile Desktop
94
Performance Overall performance score (0–100) based on Core Web Vitals and other metrics. 90+ is good.
94
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.
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.

738 ms

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

1.63 s

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

37 ms

Cumulative Layout Shift Cumulative Layout Shift — measures visual stability. How much the page layout shifts during loading. Under 0.1 is good.

0.001

Speed Index Speed Index — how quickly content is visually displayed during load. Under 3.4s is good.

738 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.

1.63 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 3 REVIEW 2 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 (669.6 KiB of 670.1 KiB)
Info::
Third-party blocking time is low (0 ms)
100%
First-party Third-party
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.

C
Image Optimization
Action
7 images, 0 KB saveable
REVIEW
7 images, 0 KB saveable
Warning::
https://www.osti.gov/assets/content/images/DOE-SC-... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.osti.gov/assets/content/images/doe-sea... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
7 images 99 KB
0 oversized -0 KB
5 legacy format
2 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

B
JS Bundles
13 scripts, 63 KB unused
REVIEW
13 scripts, 63 KB unused
Warning::
https://www.googletagmanager.com/gtag/js?id=G-MP0J...: 63 KB unused (39%)
Consider code splitting or tree shaking to reduce unused code.
Info::
Total unused JavaScript: 63 KB
63 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://www.googletagmanager.com/gtag/js?id=G-MP0JFZ283F163 KB63 KB (39%)✓3rd
https://www.osti.gov/assets/content/js/jquery-3.5.1.min.js0 KB—✓3rd
https://www.osti.gov/static/assets/content/js/jquery-3.5.1.min.js31 KB—✓3rd
https://www.osti.gov/assets/content/js/jquery-migrate.min.js?v=30 KB—✓3rd
https://www.osti.gov/assets/content/js/jquery.once.js?v=1.20 KB—✓3rd
https://www.osti.gov/assets/content/misc/drupal.js?p5yarc0 KB—✗3rd
https://www.osti.gov/assets/content/sites/all/modules/extlink/extlink.js0 KB—✓3rd
https://www.osti.gov/assets/content/sites/all/modules/ctools/js/collapsible-div.js0 KB—✓3rd
https://www.osti.gov/static/assets/content/js/jquery-migrate.min.js?v=33 KB—✓3rd
https://www.osti.gov/static/assets/content/js/jquery.once.js?v=1.22 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

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

Green Hosting

No green hosting detected

A+
Page Weight Budget
670 KB transferred, 37 requests
PASS
670 KB transferred, 37 requests
Info::
Page weighs 1.6 MB (670 KB transferred)
Info::
37 HTTP requests
Info::
Estimated 0.14 g CO2 per page load
670 KB / 2.4 MB budget
670 KB transferred
37 requests
0.14 g CO2 per page load
JavaScript 211.4 KiB 32%
CSS 142.6 KiB 21%
Fonts 134.5 KiB 20%
Images 98.7 KiB 15%
HTML 53.6 KiB 8%
Other 23.1 KiB 3%
Other 5.6 KiB 1%
Other 595 B 0%
0 2.4 MB 4.9 MB
Under budget
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
375ms total JS execution
PASS
375ms total JS execution
Info::
https://www.googletagmanager.com/gtag/js?id=G-MP0J...: 187ms CPU time
Info::
https://www.osti.gov/: 123ms CPU time
Info::
Unattributable: 65ms CPU time
Warning::
Third-party scripts: 375ms (100% of total)

Main Thread Breakdown

Script Evaluation 39% Other 20% Script Parsing & Compilation 17% Style & Layout 14% Parse HTML & CSS 6%
ScriptTotalScriptingParse/CompileParty
https://www.googletagmanager.com/gtag/js?id=G-MP0JFZ283F187ms119ms59ms3rd
https://www.osti.gov/123ms18ms3ms3rd
Unattributable65ms2ms0ms3rd
A+
Font Loading
3 fonts (135 KB)
PASS
3 fonts (135 KB)
Info::
3 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

3

135 KB total

Render-blocking

0

of 3

Dominant font-display

swap

Most common across fonts

Font loading timeline
Transfer FOIT (block) FOUT (swap)
0 ms 500 ms 1.0 s 1.5 s FCP 738 ms LCP 1.6 sdata:application/font-woff;charset=utf-8;base64,d09GRgABAAAAAE1wABIAAAAAilAAAQABAAAAAAAAAAAAAAAAAAA…font-woff;charset=utf-8... data:application/font-woff;charset=utf-8;base64,d09GRgABAAAAAE1wABIAAAAAilAAAQABAAAAAAAAAAAAAAAAAAA… — 19.4 KiB — 36 ms — font-display: swapdata:application/font-woff;charset=utf-8;base64,d09GRgABAAAAAX7oAA0AAAAChqwABAAHAAAAAAAAAAAAAAAAAAA…font-woff;charset=utf-8... data:application/font-woff;charset=utf-8;base64,d09GRgABAAAAAX7oAA0AAAAChqwABAAHAAAAAAAAAAAAAAAAAAA… — 95.7 KiB — 38 ms — font-display: swapdata:application/font-woff;charset=utf-8;base64,d09GRgABAAAAAE3MABIAAAAAiowAAQABAAAAAAAAAAAAAAAAAAA…font-woff;charset=utf-8... data:application/font-woff;charset=utf-8;base64,d09GRgABAAAAAE3MABIAAAAAiowAAQABAAAAAAAAAAAAAAAAAAA… — 19.4 KiB — 37 ms — font-display: swap
font-woff;charset=utf-8... woff swap
Size 19 KB
Load time 36 ms
Start 453 ms
Risk FOUT — text flashes from fallback to web font
  • Convert to woff2 for ~30% smaller file size
font-woff;charset=utf-8... woff swap
Size 96 KB
Load time 38 ms
Start 454 ms
Risk FOUT — text flashes from fallback to web font
  • Convert to woff2 for ~30% smaller file size
font-woff;charset=utf-8... woff swap
Size 19 KB
Load time 37 ms
Start 458 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 ~40 KB and ~80 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
No optimization needed
PASS
No optimization needed
Info::
No resource hint issues
A
Page Weight Inventory
37 resources · 670 KB · 63 KB savings available
PASS
37 resources · 670 KB · 63 KB savings available
Info::
Within 1MB page-weight target
Got: 670 KB
Info::
~63 KB of savings available
Warning::
36 third-party resources (100% of weight)
37 resources · 670.1 KiB · 36 third-party Within 1MB page-weight target
JavaScript 32% · 213.9 KiB
CSS 21% · 143.4 KiB
Font 20% · 134.5 KiB
Image 17% · 112.1 KiB
Document 10% · 65.6 KiB
Other 0% · 595 B

~63.2 KiB of savings available

Remove unused JavaScript: 63.2 KiB
Network Waterfall
37 requests over 744ms
INFO
0 ms 500 ms 1.0 s 1.5 s FCP 738 ms LCP 1.6 shttps://osti.gov// https://osti.gov/ — 301 — 482 B — 104 ms — http/1.1https://www.osti.gov/www.osti.gov/ https://www.osti.gov/ — 200 — 53.6 KiB — 150 ms — http/1.1https://www.osti.gov/loginwww.osti.gov/login https://www.osti.gov/login — 200 — 5.9 KiB — 118 ms — http/1.1https://www.osti.gov/assets/content/css/fontawesome.font_.csswww.osti.gov/assets/content/css/fon... https://www.osti.gov/assets/content/css/fontawesome.font_.css — 302 — 414 B — 58 ms — http/1.1https://www.osti.gov/assets/content/css/roboto.font_.csswww.osti.gov/assets/content/css/rob... https://www.osti.gov/assets/content/css/roboto.font_.css — 302 — 409 B — 78 ms — http/1.1https://www.googletagmanager.com/gtag/js?id=G-MP0JFZ283Fwww.googletagmanager.com/gtag/js?id... https://www.googletagmanager.com/gtag/js?id=G-MP0JFZ283F — 200 — 163.4 KiB — 63 ms — h2https://www.osti.gov/assets/content/images/doe-seal-white-600-33-min.pngwww.osti.gov/assets/content/images/... https://www.osti.gov/assets/content/images/doe-seal-white-600-33-min.png — 302 — 426 B — 177 ms — http/1.1https://www.osti.gov/assets/content/images/OSTItitle_325-min.pngwww.osti.gov/assets/content/images/... https://www.osti.gov/assets/content/images/OSTItitle_325-min.png — 302 — 418 B — 177 ms — http/1.1https://www.osti.gov/assets/content/images/DOE-SC-OSTI-RGB-Logo.docx_:user:_rId14_:msword:_media_image6.svgwww.osti.gov/assets/content/images/... https://www.osti.gov/assets/content/images/DOE-SC-OSTI-RGB-Logo.docx_:user:_rId14_:msword:_media_image6.svg — 302 — 432 B — 182 ms — http/1.1https://www.osti.gov/assets/content/js/jquery-3.5.1.min.jswww.osti.gov/assets/content/js/jque... https://www.osti.gov/assets/content/js/jquery-3.5.1.min.js — 302 — 426 B — 100 ms — http/1.1https://www.osti.gov/static/assets/content/css/fontawesome.font_.csswww.osti.gov/static/assets/content/... https://www.osti.gov/static/assets/content/css/fontawesome.font_.css — 200 — 105.3 KiB — 109 ms — http/1.1https://www.osti.gov/static/assets/content/css/roboto.font_.csswww.osti.gov/static/assets/content/... https://www.osti.gov/static/assets/content/css/roboto.font_.css — 200 — 37.3 KiB — 59 ms — http/1.1https://www.osti.gov/static/assets/content/js/jquery-3.5.1.min.jswww.osti.gov/static/assets/content/... https://www.osti.gov/static/assets/content/js/jquery-3.5.1.min.js — 200 — 30.7 KiB — 34 ms — http/1.1https://www.osti.gov/assets/content/js/jquery-migrate.min.js?v=3www.osti.gov/assets/content/js/jque... https://www.osti.gov/assets/content/js/jquery-migrate.min.js?v=3 — 302 — 431 B — 109 ms — http/1.1https://www.osti.gov/assets/content/js/jquery.once.js?v=1.2www.osti.gov/assets/content/js/jque... https://www.osti.gov/assets/content/js/jquery.once.js?v=1.2 — 302 — 426 B — 85 ms — http/1.1https://www.osti.gov/assets/content/misc/drupal.js?p5yarcwww.osti.gov/assets/content/misc/dr... https://www.osti.gov/assets/content/misc/drupal.js?p5yarc — 302 — 424 B — 78 ms — http/1.1https://www.google-analytics.com/g/collect?v=2&tid=G-MP0JFZ283F&gtm=45je64k0v9116238154za200zd9116238154&_p=1776896034123&gcd=13l3l3l3l1l1&npa=0&dma=0&are=1&cid=474704759.1776896034&frm=0&pscdl=noapi&rcb=2&sr=800x600&uaa=x86&uab=64&uafvl=Not-A.Brand%3B24.0.0.0%7CChromium%3B146.0.7680.164&uam=&uamb=0&uap=macOS&uapv=10.15.7&uaw=0&ul=en-us&_s=1&tag_exp=0~115616986~115938466~115938469~117266400~117512543&sid=1776896034&sct=1&seg=0&dl=https%3A%2F%2Fwww.osti.gov%2F&dt=OSTI.GOV%20%7C%20U.S.%20Department%20of%20Energy%20Office%20of%20Scientific%20and%20Technical%20Information&en=page_view&_fv=1&_nsi=1&_ss=1&_ee=1&tfd=436www.google-analytics.com/g/collect?... https://www.google-analytics.com/g/collect?v=2&tid=G-MP0JFZ283F&gtm=45je64k0v9116238154za200zd9116238154&_p=1776896034123&gcd=13l3l3l3l1l1&npa=0&dma=0&are=1&cid=474704759.1776896034&frm=0&pscdl=noapi&rcb=2&sr=800x600&uaa=x86&uab=64&uafvl=Not-A.Brand%3B24.0.0.0%7CChromium%3B146.0.7680.164&uam=&uamb=0&uap=macOS&uapv=10.15.7&uaw=0&ul=en-us&_s=1&tag_exp=0~115616986~115938466~115938469~117266400~117512543&sid=1776896034&sct=1&seg=0&dl=https%3A%2F%2Fwww.osti.gov%2F&dt=OSTI.GOV%20%7C%20U.S.%20Department%20of%20Energy%20Office%20of%20Scientific%20and%20Technical%20Information&en=page_view&_fv=1&_nsi=1&_ss=1&_ee=1&tfd=436 — 204 — 48 B — 93 ms — h2https://www.google-analytics.com/g/collect?v=2&tid=G-4W8DTEJH5Q&gtm=45je64k0v9116238154za200zd9116238154&_p=1776896034123&gcd=13l3l3l3l1l1&npa=0&dma=0&are=1&cid=474704759.1776896034&frm=0&pscdl=noapi&rcb=2&sr=800x600&uaa=x86&uab=64&uafvl=Not-A.Brand%3B24.0.0.0%7CChromium%3B146.0.7680.164&uam=&uamb=0&uap=macOS&uapv=10.15.7&uaw=0&ul=en-us&_s=1&tag_exp=0~115616986~115938466~115938469~117266400~117512543&sid=1776896034&sct=1&seg=0&dl=https%3A%2F%2Fwww.osti.gov%2F&dt=OSTI.GOV%20%7C%20U.S.%20Department%20of%20Energy%20Office%20of%20Scientific%20and%20Technical%20Information&en=page_view&_fv=1&_ss=1&_ee=1&tfd=442www.google-analytics.com/g/collect?... https://www.google-analytics.com/g/collect?v=2&tid=G-4W8DTEJH5Q&gtm=45je64k0v9116238154za200zd9116238154&_p=1776896034123&gcd=13l3l3l3l1l1&npa=0&dma=0&are=1&cid=474704759.1776896034&frm=0&pscdl=noapi&rcb=2&sr=800x600&uaa=x86&uab=64&uafvl=Not-A.Brand%3B24.0.0.0%7CChromium%3B146.0.7680.164&uam=&uamb=0&uap=macOS&uapv=10.15.7&uaw=0&ul=en-us&_s=1&tag_exp=0~115616986~115938466~115938469~117266400~117512543&sid=1776896034&sct=1&seg=0&dl=https%3A%2F%2Fwww.osti.gov%2F&dt=OSTI.GOV%20%7C%20U.S.%20Department%20of%20Energy%20Office%20of%20Scientific%20and%20Technical%20Information&en=page_view&_fv=1&_ss=1&_ee=1&tfd=442 — 204 — 547 B — 80 ms — h2https://www.osti.gov/static/assets/content/images/doe-seal-white-600-33-min.pngwww.osti.gov/static/assets/content/... https://www.osti.gov/static/assets/content/images/doe-seal-white-600-33-min.png — 200 — 9.0 KiB — 36 ms — http/1.1https://www.osti.gov/static/assets/content/images/OSTItitle_325-min.pngwww.osti.gov/static/assets/content/... https://www.osti.gov/static/assets/content/images/OSTItitle_325-min.png — 200 — 2.3 KiB — 34 ms — http/1.1https://www.osti.gov/static/assets/content/images/DOE-SC-OSTI-RGB-Logo.docx_:user:_rId14_:msword:_media_image6.svgwww.osti.gov/static/assets/content/... https://www.osti.gov/static/assets/content/images/DOE-SC-OSTI-RGB-Logo.docx_:user:_rId14_:msword:_media_image6.svg — 200 — 50.2 KiB — 56 ms — http/1.1data:application/font-woff;charset=utf-8;base64,d09GRgABAAAAAE1wABIAAAAAilAAAQABAAAAAAAAAAAAAAAAAAA…data:application/font-woff;charset=... data:application/font-woff;charset=utf-8;base64,d09GRgABAAAAAE1wABIAAAAAilAAAQABAAAAAAAAAAAAAAAAAAA… — 200 — 19.4 KiB — 36 ms — datadata:application/font-woff;charset=utf-8;base64,d09GRgABAAAAAX7oAA0AAAAChqwABAAHAAAAAAAAAAAAAAAAAAA…data:application/font-woff;charset=... data:application/font-woff;charset=utf-8;base64,d09GRgABAAAAAX7oAA0AAAAChqwABAAHAAAAAAAAAAAAAAAAAAA… — 200 — 95.7 KiB — 38 ms — datadata:application/font-woff;charset=utf-8;base64,d09GRgABAAAAAE3MABIAAAAAiowAAQABAAAAAAAAAAAAAAAAAAA…data:application/font-woff;charset=... data:application/font-woff;charset=utf-8;base64,d09GRgABAAAAAE3MABIAAAAAiowAAQABAAAAAAAAAAAAAAAAAAA… — 200 — 19.4 KiB — 37 ms — datahttps://www.osti.gov/assets/content/sites/all/modules/extlink/extlink.jswww.osti.gov/assets/content/sites/a... https://www.osti.gov/assets/content/sites/all/modules/extlink/extlink.js — 302 — 439 B — 44 ms — http/1.1https://www.osti.gov/assets/content/sites/all/modules/ctools/js/collapsible-div.jswww.osti.gov/assets/content/sites/a... https://www.osti.gov/assets/content/sites/all/modules/ctools/js/collapsible-div.js — 302 — 449 B — 43 ms — http/1.1https://www.osti.gov/static/assets/content/js/jquery-migrate.min.js?v=3www.osti.gov/static/assets/content/... https://www.osti.gov/static/assets/content/js/jquery-migrate.min.js?v=3 — 200 — 3.1 KiB — 34 ms — http/1.1https://www.osti.gov/static/assets/content/js/jquery.once.js?v=1.2www.osti.gov/static/assets/content/... https://www.osti.gov/static/assets/content/js/jquery.once.js?v=1.2 — 200 — 1.5 KiB — 34 ms — http/1.1https://www.osti.gov/static/assets/content/misc/drupal.js?p5yarcwww.osti.gov/static/assets/content/... https://www.osti.gov/static/assets/content/misc/drupal.js?p5yarc — 200 — 7.4 KiB — 36 ms — http/1.1https://www.osti.gov/static/assets/content/sites/all/modules/ctools/js/collapsible-div.jswww.osti.gov/static/assets/content/... https://www.osti.gov/static/assets/content/sites/all/modules/ctools/js/collapsible-div.js — 200 — 2.9 KiB — 33 ms — http/1.1
0 ms 500 ms 1.0 s 1.5 s FCP 738 ms LCP 1.6 shttps://osti.gov// https://osti.gov/ — 301 — 482 B — 104 ms — http/1.1https://www.osti.gov/www.osti.gov/ https://www.osti.gov/ — 200 — 53.6 KiB — 150 ms — http/1.1https://www.osti.gov/loginwww.osti.gov/login https://www.osti.gov/login — 200 — 5.9 KiB — 118 ms — http/1.1https://www.osti.gov/assets/content/css/fontawesome.font_.csswww.osti.gov/assets/content/css/fon... https://www.osti.gov/assets/content/css/fontawesome.font_.css — 302 — 414 B — 58 ms — http/1.1https://www.osti.gov/assets/content/css/roboto.font_.csswww.osti.gov/assets/content/css/rob... https://www.osti.gov/assets/content/css/roboto.font_.css — 302 — 409 B — 78 ms — http/1.1https://www.googletagmanager.com/gtag/js?id=G-MP0JFZ283Fwww.googletagmanager.com/gtag/js?id... https://www.googletagmanager.com/gtag/js?id=G-MP0JFZ283F — 200 — 163.4 KiB — 63 ms — h2https://www.osti.gov/assets/content/images/doe-seal-white-600-33-min.pngwww.osti.gov/assets/content/images/... https://www.osti.gov/assets/content/images/doe-seal-white-600-33-min.png — 302 — 426 B — 177 ms — http/1.1https://www.osti.gov/assets/content/images/OSTItitle_325-min.pngwww.osti.gov/assets/content/images/... https://www.osti.gov/assets/content/images/OSTItitle_325-min.png — 302 — 418 B — 177 ms — http/1.1https://www.osti.gov/assets/content/images/DOE-SC-OSTI-RGB-Logo.docx_:user:_rId14_:msword:_media_image6.svgwww.osti.gov/assets/content/images/... https://www.osti.gov/assets/content/images/DOE-SC-OSTI-RGB-Logo.docx_:user:_rId14_:msword:_media_image6.svg — 302 — 432 B — 182 ms — http/1.1https://www.osti.gov/assets/content/js/jquery-3.5.1.min.jswww.osti.gov/assets/content/js/jque... https://www.osti.gov/assets/content/js/jquery-3.5.1.min.js — 302 — 426 B — 100 ms — http/1.1https://www.osti.gov/static/assets/content/css/fontawesome.font_.csswww.osti.gov/static/assets/content/... https://www.osti.gov/static/assets/content/css/fontawesome.font_.css — 200 — 105.3 KiB — 109 ms — http/1.1https://www.osti.gov/static/assets/content/css/roboto.font_.csswww.osti.gov/static/assets/content/... https://www.osti.gov/static/assets/content/css/roboto.font_.css — 200 — 37.3 KiB — 59 ms — http/1.1https://www.osti.gov/static/assets/content/js/jquery-3.5.1.min.jswww.osti.gov/static/assets/content/... https://www.osti.gov/static/assets/content/js/jquery-3.5.1.min.js — 200 — 30.7 KiB — 34 ms — http/1.1https://www.osti.gov/assets/content/js/jquery-migrate.min.js?v=3www.osti.gov/assets/content/js/jque... https://www.osti.gov/assets/content/js/jquery-migrate.min.js?v=3 — 302 — 431 B — 109 ms — http/1.1https://www.osti.gov/assets/content/js/jquery.once.js?v=1.2www.osti.gov/assets/content/js/jque... https://www.osti.gov/assets/content/js/jquery.once.js?v=1.2 — 302 — 426 B — 85 ms — http/1.1https://www.osti.gov/assets/content/misc/drupal.js?p5yarcwww.osti.gov/assets/content/misc/dr... https://www.osti.gov/assets/content/misc/drupal.js?p5yarc — 302 — 424 B — 78 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 375ms · 217KB · $5/mo
Google Tag Manager
Tag Manager
Optional
Execution 187ms
Transfer 163 KB
Unused 39%
Monthly Cost $2/mo
www.osti.gov
Other
Optional
Execution 123ms
Transfer 54 KB
Monthly Cost $2/mo
Unattributable
Other
Optional
Execution 65ms
Transfer 0 KB
Monthly Cost $1/mo

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

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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