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Performance

· 14 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
74
GRADE
C
FIX
2
REVIEW
4
PASS
6
INFO
2

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

Mobile Desktop
41
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.
81
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.

4.28 s

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

14.15 s

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

1.03 s

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.

4.97 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.

16.51 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
14
6 PASS 4 REVIEW 2 FIX
F
Page Weight Budget
Action
2.7 MB transferred, 89 requests
FIX
2.7 MB transferred, 89 requests
Warning::
Page weighs 5.2 MB (2.7 MB transferred)
Warning::
Images are 1.5 MB — compress or use modern formats
Convert images to WebP/AVIF and resize to display dimensions to reduce transfer size.
Got: 1.5 MB
Warning::
JavaScript is 817 KB — consider code splitting or lazy loading
Large JavaScript bundles delay interactivity. Split code by route or defer non-critical scripts.
Got: 817 KB
Info::
89 HTTP requests
Info::
Estimated 0.56 g CO2 per page load
2.7 MB / 2.4 MB budget
2.7 MB transferred
89 requests
0.56 g CO2 per page load
Images 1.5 MiB 58%
JavaScript 816.7 KiB 30%
Fonts 166.0 KiB 6%
CSS 118.0 KiB 4%
HTML 47.4 KiB 2%
Other 2.8 KiB 0%
Other 1.9 KiB 0%
Other 591 B 0%
Other 550 B 0%
0 2.4 MB 4.9 MB
Over budget

Convert images to WebP/AVIF and resize to display dimensions to reduce transfer size.

Why this matters

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.

Why this matters

JavaScript bundle is large — code-split routes and lazy-load off-screen components to defer.

Source: web.dev

F
JS Execution Cost
Action
4393ms total JS execution
FIX
4393ms total JS execution
Warning::
https://www.stanford.edu/: 1387ms CPU time
Warning::
Unattributable: 483ms CPU time
Warning::
https://www.googletagmanager.com/gtm.js?id=GTM-T4N...: 463ms CPU time
Warning::
https://www.stanford.edu/wp-content/themes/homesit...: 329ms CPU time
Warning::
https://www.googletagmanager.com/gtag/js?id=G-RBCP...: 319ms CPU time
Warning::
Third-party scripts: 2497ms (57% of total)

Main Thread Breakdown

Script Evaluation 47% Style & Layout 20% Other 18% Script Parsing & Compilation 9% Parse HTML & CSS 4%
ScriptTotalScriptingParse/CompileParty
https://www.stanford.edu/1387ms127ms29ms1st
Unattributable483ms32ms0ms3rd
https://www.googletagmanager.com/gtm.js?id=GTM-T4N2WTT463ms387ms66ms3rd
https://www.stanford.edu/wp-content/themes/homesite17/js/dist/master.min.js?ver=2021.04.15.11.26329ms202ms9ms1st
https://www.googletagmanager.com/gtag/js?id=G-RBCPHN00S7&cx=c&gtm=4e6411319ms259ms57ms3rd
https://www.googletagmanager.com/gtag/js?id=G-E08J4Q7DG7&cx=c&_slc=1307ms250ms56ms3rd
https://js-agent.newrelic.com/nr-spa-1.312.0.min.js246ms201ms13ms3rd
https://script.hotjar.com/modules.6a0f3932cb1341a35c18.js205ms169ms31ms3rd
https://connect.facebook.net/en_US/fbevents.js175ms126ms47ms3rd
https://connect.facebook.net/signals/config/1199096620574484?v=2.9.291&r=stable&domain=www.stanford.edu&hme=295b1b33901e14aeab879c0b58f907ef4d5f44fdd19814310771af911c5f6ac8&ex_m=102%2C198%2C147%2C22%2C70%2C71%2C139%2C66%2C65%2C11%2C155%2C88%2C16%2C132%2C124%2C37%2C73%2C76%2C130%2C152%2C157%2C8%2C4%2C5%2C7%2C6%2C3%2C89%2C99%2C158%2C163%2C212%2C60%2C179%2C180%2C53%2C267%2C30%2C72%2C224%2C223%2C222%2C23%2C32%2C101%2C59%2C10%2C61%2C95%2C96%2C97%2C103%2C127%2C31%2C29%2C129%2C126%2C125%2C148%2C74%2C151%2C149%2C150%2C48%2C58%2C120%2C15%2C154%2C43%2C254%2C255%2C253%2C26%2C27%2C28%2C46%2C140%2C75%2C110%2C18%2C20%2C42%2C38%2C40%2C39%2C81%2C90%2C94%2C108%2C138%2C141%2C44%2C109%2C24%2C21%2C116%2C67%2C35%2C143%2C142%2C144%2C135%2C133%2C25%2C34%2C57%2C107%2C153%2C68%2C17%2C145%2C112%2C79%2C64%2C19%2C83%2C84%2C113%2C82%2C33%2C284%2C205%2C194%2C195%2C193%2C287%2C279%2C50%2C206%2C105%2C128%2C78%2C118%2C52%2C45%2C47%2C111%2C117%2C123%2C56%2C62%2C51%2C54%2C98%2C156%2C1%2C121%2C14%2C119%2C12%2C2%2C55%2C91%2C63%2C115%2C87%2C86%2C159%2C160%2C92%2C93%2C9%2C122%2C100%2C49%2C136%2C85%2C77%2C69%2C114%2C104%2C41%2C137%2C0%2C80%2C131%2C134%2C146%2C36%2C106%2C13%2C161124ms101ms22ms3rd

Showing top 10 of 14 scripts

B
Third-Party Impact
46% third-party, 0 ms blocking
REVIEW
46% third-party, 0 ms blocking
Info::
Third-party code accounts for 46% of page weight (1.2 MiB of 2.7 MiB)
Info::
Third-party blocking time is low (0 ms)
54%
46%
First-party Third-party
C
Image Optimization
Action
40 images, 0 KB saveable
REVIEW
40 images, 0 KB saveable
Warning::
https://www.stanford.edu/wp-content/uploads/2022/0... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.stanford.edu/wp-content/uploads/2022/0... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.stanford.edu/wp-content/uploads/2023/0... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.stanford.edu/wp-content/uploads/2022/0... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.stanford.edu/wp-content/uploads/2025/1... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.stanford.edu/wp-content/uploads/2025/1... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.stanford.edu/wp-content/uploads/2025/1... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.stanford.edu/wp-content/uploads/2023/0... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.stanford.edu/wp-content/uploads/2023/1... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.stanford.edu/wp-content/uploads/2026/0... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.stanford.edu/wp-content/uploads/2025/0... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.stanford.edu/wp-content/uploads/2021/1... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.stanford.edu/wp-content/uploads/2025/1... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.stanford.edu/wp-content/uploads/2022/0... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.stanford.edu/wp-content/uploads/2025/0... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.stanford.edu/wp-content/uploads/2022/0... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.stanford.edu/wp-content/uploads/2024/0... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.stanford.edu/wp-content/uploads/2022/0... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.stanford.edu/wp-content/uploads/2025/1... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.stanford.edu/wp-content/uploads/2022/0... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.stanford.edu/wp-content/uploads/2023/0... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.stanford.edu/wp-content/uploads/2022/0... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
40 images 1.5 MB
0 oversized -0 KB
10 legacy format
22 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

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

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

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

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

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

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

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
20 scripts, 259 KB unused
REVIEW
20 scripts, 259 KB unused
Warning::
https://www.googletagmanager.com/gtm.js?id=GTM-T4N...: 65 KB unused (41%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.googletagmanager.com/gtag/js?id=G-E08J...: 63 KB unused (43%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.googletagmanager.com/gtag/js?id=G-RBCP...: 59 KB unused (40%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://script.hotjar.com/modules.6a0f3932cb1341a3...: 38 KB unused (67%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://connect.facebook.net/en_US/fbevents.js: 34 KB unused (36%)
Consider code splitting or tree shaking to reduce unused code.
Info::
Total unused JavaScript: 259 KB
259 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://www.googletagmanager.com/gtm.js?id=GTM-T4N2WTT158 KB65 KB (41%)✓3rd
https://www.googletagmanager.com/gtag/js?id=G-E08J4Q7DG7&cx=c&_slc=1147 KB63 KB (43%)✓3rd
https://www.googletagmanager.com/gtag/js?id=G-RBCPHN00S7&cx=c&gtm=4e6411146 KB59 KB (40%)✓3rd
https://script.hotjar.com/modules.6a0f3932cb1341a35c18.js57 KB38 KB (67%)✓3rd
https://connect.facebook.net/en_US/fbevents.js95 KB34 KB (36%)✓3rd
https://www.stanford.edu/wp-content/plugins/awesome-weather-pro/js/awesome-weather-widget-frontend.js?ver=1.12 KB—✓1st
https://www.stanford.edu/wp-content/plugins/stanford-fb-pixel/pixel.js?ver=1.0.11 KB—✓1st
https://www.stanford.edu/wp-content/themes/homesite17/js/dist/master.min.js?ver=2021.04.15.11.2623 KB—✓1st
https://siteimproveanalytics.com/js/siteanalyze_80352.js20 KB—✓3rd
https://www.stanford.edu/wp-includes/js/jquery/jquery.min.js?ver=3.7.135 KB—✓1st

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

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+
Font Loading
8 fonts (166 KB)
PASS
8 fonts (166 KB)
Info::
8 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

8

166 KB total

Render-blocking

0

of 8

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 14.0 s FCP 4.3 s LCP 14.2 shttps://fonts.gstatic.com/s/sourcesanspro/v23/6xK3dSBYKcSV-LCoeQqfX1RYOo3qOK7lujVj9w.woff26xK3dSBYKcSV-LCoeQqfX1R... https://fonts.gstatic.com/s/sourcesanspro/v23/6xK3dSBYKcSV-LCoeQqfX1RYOo3qOK7lujVj9w.woff2 — 14.5 KiB — 0 ms — font-display: swaphttps://www.stanford.edu/wp-content/themes/homesite17/fonts/Stanford.ttf?a9awv8Stanford.ttf https://www.stanford.edu/wp-content/themes/homesite17/fonts/Stanford.ttf?a9awv8 — 4.5 KiB — 0 ms — font-display: swaphttps://www.stanford.edu/wp-content/themes/homesite17/fonts/fontawesome-webfont.woff2?v=4.7.0fontawesome-webfont.woff2 https://www.stanford.edu/wp-content/themes/homesite17/fonts/fontawesome-webfont.woff2?v=4.7.0 — 75.7 KiB — 0 ms — font-display: swaphttps://fonts.gstatic.com/s/sourcesanspro/v23/6xKydSBYKcSV-LCoeQqfX1RYOo3i54rwlxdu3cOWxw.woff26xKydSBYKcSV-LCoeQqfX1R... https://fonts.gstatic.com/s/sourcesanspro/v23/6xKydSBYKcSV-LCoeQqfX1RYOo3i54rwlxdu3cOWxw.woff2 — 14.6 KiB — 0 ms — font-display: swaphttps://fonts.gstatic.com/s/sourcesanspro/v23/6xKydSBYKcSV-LCoeQqfX1RYOo3ig4vwlxdu3cOWxw.woff26xKydSBYKcSV-LCoeQqfX1R... https://fonts.gstatic.com/s/sourcesanspro/v23/6xKydSBYKcSV-LCoeQqfX1RYOo3ig4vwlxdu3cOWxw.woff2 — 14.4 KiB — 0 ms — font-display: swaphttps://fonts.gstatic.com/s/sourcesanspro/v23/6xKydSBYKcSV-LCoeQqfX1RYOo3iu4nwlxdu3cOWxw.woff26xKydSBYKcSV-LCoeQqfX1R... https://fonts.gstatic.com/s/sourcesanspro/v23/6xKydSBYKcSV-LCoeQqfX1RYOo3iu4nwlxdu3cOWxw.woff2 — 13.9 KiB — 0 ms — font-display: swaphttps://fonts.gstatic.com/s/sourcesanspro/v23/6xKydSBYKcSV-LCoeQqfX1RYOo3ik4zwlxdu3cOWxw.woff26xKydSBYKcSV-LCoeQqfX1R... https://fonts.gstatic.com/s/sourcesanspro/v23/6xKydSBYKcSV-LCoeQqfX1RYOo3ik4zwlxdu3cOWxw.woff2 — 14.5 KiB — 0 ms — font-display: swaphttps://fonts.gstatic.com/s/sourcesanspro/v23/6xK1dSBYKcSV-LCoeQqfX1RYOo3qPZ7nsDJB9cme.woff26xK1dSBYKcSV-LCoeQqfX1R... https://fonts.gstatic.com/s/sourcesanspro/v23/6xK1dSBYKcSV-LCoeQqfX1RYOo3qPZ7nsDJB9cme.woff2 — 13.9 KiB — 0 ms — font-display: swap
6xK3dSBYKcSV-LCoeQqfX1R... woff2 swap
Size 15 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
Stanford.ttf ttf swap
Size 5 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
  • Convert to woff2 for ~30% smaller file size
fontawesome-webfont.woff2 woff2 swap
Size 76 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
6xKydSBYKcSV-LCoeQqfX1R... woff2 swap
Size 15 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
6xKydSBYKcSV-LCoeQqfX1R... woff2 swap
Size 14 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
6xKydSBYKcSV-LCoeQqfX1R... woff2 swap
Size 14 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
6xKydSBYKcSV-LCoeQqfX1R... woff2 swap
Size 14 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
6xK1dSBYKcSV-LCoeQqfX1R... woff2 swap
Size 14 KB
Load time 0 ms
Start 0 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)

Fixing the unchecked items could save ~1 KB and ~2 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
2 hints, 0 missing preconnects
PASS
2 hints, 0 missing preconnects
Info::
Page uses 2 resource hint(s)

Current Resource Hints

preconnect
—
preload
—
dns-prefetch
2
prefetch
—

2 resource hints configured

A
HTTP Caching
max-age=604800 (1 week)
PASS
max-age=604800 (1 week)
Info::
Cache-Control header is set
Got: public, max-age=604800
Info::
Effective TTL: 1 week (max-age=604800)
Info::
No ETag or Last-Modified header
Conditional requests (304 Not Modified) are not possible without validators.
Cache-Control

public, max-age=604800

DirectiveValueMeaning
public—Any cache may store this response
max-age604800Cache for 1 week
Effective TTL: 604800 seconds
Network Waterfall
89 requests over 0ms
INFO

Performance analysis not available for this result.

Third-Party Script Cost
Per-script blocking time, transfer cost, and cache headers
INFO
57% of JavaScript execution is third-party
First-party Third-party 2497ms · 711KB · $33/mo
Unattributable
Other
Costly
Execution 483ms
Transfer 0 KB
Monthly Cost $6/mo
Google Tag Manager
Tag Manager
Costly
Execution 463ms
Transfer 158 KB
Unused 41%
Monthly Cost $6/mo
Google Tag Manager
Tag Manager
Costly
Execution 319ms
Transfer 146 KB
Unused 40%
Monthly Cost $4/mo
Google Tag Manager
Tag Manager
Costly
Execution 307ms
Transfer 147 KB
Unused 43%
Monthly Cost $4/mo
js-agent.newrelic.com
Other
Costly
Execution 246ms
Transfer 30 KB
Monthly Cost $3/mo
Hotjar
Session Replay
Costly
Execution 205ms
Transfer 57 KB
Unused 67%
Monthly Cost $3/mo
Facebook Pixel
Advertising
Optional
Execution 175ms
Transfer 95 KB
Unused 36%
Monthly Cost $2/mo
Facebook Pixel
Advertising
Optional
Execution 124ms
Transfer 37 KB
Monthly Cost $2/mo
siteimproveanalytics.com
Other
Optional
Execution 95ms
Transfer 20 KB
Monthly Cost $1/mo
Google Analytics
Analytics
Optional
Execution 78ms
Transfer 21 KB
Monthly Cost $1/mo

These scripts may cost more than they're worth

  • Unattributable adds 483ms and costs ~$6/month
  • Google Tag Manager adds 463ms and costs ~$6/month
  • Google Tag Manager adds 319ms and costs ~$4/month
  • Google Tag Manager adds 307ms and costs ~$4/month
  • js-agent.newrelic.com adds 246ms and costs ~$3/month
  • Hotjar adds 205ms and costs ~$3/month

57% of JavaScript execution time comes from third-party scripts.

Why this matters

Third-party scripts (analytics, ads, social, A/B testing) often dominate execution time — every one is a perf-and-privacy tax.

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Each third-party script is a black box: you don't control when it loads, what it executes, or how much it grows. They often account for a major share of total blocking time on average sites (HTTP Archive's Web Almanac documents the trend). Audit which ones you actually need, defer the rest, and use facade patterns (lite-youtube, lite-vimeo) for embedded media.

Source: web.dev / HTTP Archive Web Almanac

Unattributable takes 483ms 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 463ms 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 319ms 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 307ms 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

js-agent.newrelic.com takes 246ms 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

Hotjar takes 205ms 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

67% of Hotjar'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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