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Performance

· 17 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
79
GRADE
C
FIX
3
REVIEW
4
PASS
8
INFO
2

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

Mobile Desktop
58
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.
91
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.

5.24 s

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

11.62 s

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

149 ms

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

0.002

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

6.33 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.

11.62 s

Page Load Progression

586 ms
1.2 s
1.8 s
2.3 s
2.9 s
3.5 s
4.1 s
4.7 s
Checks
17
8 PASS 4 REVIEW 3 FIX
F
Page Weight Budget
Action
19.9 MB transferred, 54 requests
FIX
19.9 MB transferred, 54 requests
Critical::
Page weighs 20.6 MB (19.9 MB transferred)
Warning::
Images are 5.8 MB — compress or use modern formats
Convert images to WebP/AVIF and resize to display dimensions to reduce transfer size.
Got: 5.8 MB
Info::
CSS is 328 KB — consider purging unused styles
Remove unused CSS rules with tools like PurgeCSS to reduce stylesheet size.
Got: 328 KB
Info::
54 HTTP requests
Info::
Estimated 4.2 g CO2 per page load
19.9 MB / 2.4 MB budget
19.9 MB transferred
54 requests
4.2 g CO2 per page load
Other 13.0 MiB 66%
Images 5.8 MiB 29%
JavaScript 455.8 KiB 2%
CSS 328.2 KiB 2%
HTML 140.3 KiB 1%
Fonts 103.6 KiB 1%
Other 15.0 KiB 0%
Other 543 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

Remove unused CSS rules with tools like PurgeCSS to reduce stylesheet size.

Why this matters

CSS bundle is large — purge unused styles (PurgeCSS, Tailwind JIT) to reduce CSS payload.

Source: web.dev

D
JS Execution Cost
Action
2565ms total JS execution
FIX
2565ms total JS execution
Warning::
Unattributable: 1052ms CPU time
Warning::
https://uci.edu/: 986ms CPU time
Info::
https://www.googletagmanager.com/gtm.js?id=GTM-M2P...: 175ms CPU time
Info::
https://www.googletagmanager.com/gtag/js?id=G-WZF0...: 169ms CPU time
Info::
https://siteimproveanalytics.com/js/siteanalyze_83...: 129ms CPU time
Warning::
Third-party scripts: 1525ms (59% of total)

Main Thread Breakdown

Other 49% Script Evaluation 20% Style & Layout 18% Rendering 6% Script Parsing & Compilation 4%
ScriptTotalScriptingParse/CompileParty
Unattributable1052ms78ms0ms3rd
https://uci.edu/986ms8ms1ms1st
https://www.googletagmanager.com/gtm.js?id=GTM-M2P2J94175ms126ms34ms3rd
https://www.googletagmanager.com/gtag/js?id=G-WZF0XCWWWK&cx=c&gtm=4e64h1169ms124ms44ms3rd
https://siteimproveanalytics.com/js/siteanalyze_8343.js129ms109ms18ms3rd
https://uci.edu/_assets/js/main.js53ms22ms5ms1st
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
Image Optimization
33 images, 0 KB saveable
REVIEW
33 images, 0 KB saveable
Info::
All images are well-optimized
33 images 5.8 MB
0 oversized -0 KB
32 legacy format
0 missing dimensions CLS risk
C
JS Bundles
Action
10 scripts, 229 KB unused
REVIEW
10 scripts, 229 KB unused
Warning::
https://www.googletagmanager.com/gtag/js?id=G-WZF0...: 65 KB unused (43%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.googletagmanager.com/gtm.js?id=GTM-M2P...: 65 KB unused (53%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://uci.edu/_assets/js/vendor.js: 40 KB unused (73%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://uci.edu/_assets/js/main.js: 37 KB unused (78%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://code.jquery.com/jquery-3.7.1.min.js: 22 KB unused (73%)
Consider code splitting or tree shaking to reduce unused code.
Info::
Total unused JavaScript: 229 KB
229 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://www.googletagmanager.com/gtag/js?id=G-WZF0XCWWWK&cx=c&gtm=4e64h1151 KB65 KB (43%)✓3rd
https://www.googletagmanager.com/gtm.js?id=GTM-M2P2J94123 KB65 KB (53%)✓3rd
https://uci.edu/_assets/js/vendor.js55 KB40 KB (73%)✓1st
https://uci.edu/_assets/js/main.js48 KB37 KB (78%)✓1st
https://code.jquery.com/jquery-3.7.1.min.js30 KB22 KB (73%)✓3rd
https://uci.edu/_assets/js/plugins/modernizr.js6 KB—✓1st
https://uci.edu/_assets/js/scpa-min.js1 KB—✓1st
https://uci.edu/_assets/js/home.js1 KB—✓1st
https://uci.edu/_assets/js/cookie-banner.js1 KB—✓1st
https://siteimproveanalytics.com/js/siteanalyze_8343.js41 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

C
Page Weight Inventory
Action
54 resources · 19.9 MB · 229 KB savings available
REVIEW
54 resources · 19.9 MB · 229 KB savings available
Warning::
Page weight 18.9 MB over 1MB target
Got: 19.9 MB Expected: ≤ 1 MB
Info::
~229 KB of savings available
Info::
12 third-party resources (2% of weight)
Info::
11 resources over 200KB
54 resources · 19.9 MiB · 12 third-party 18.9 MiB over 1MB target
Media 66% · 13.0 MiB
Image 29% · 5.8 MiB
JavaScript 2% · 455.8 KiB
CSS 2% · 328.2 KiB
Document 1% · 140.3 KiB
Font 1% · 103.6 KiB
Other 0% · 543 B

~228.5 KiB of savings available

Remove unused JavaScript: 228.5 KiB
C
Green Hosting
Action
Whether the site is served from green-energy infrastructure
REVIEW

Green Hosting

No green hosting detected

A+
Third-Party Impact
2% third-party, 0 ms blocking
PASS
2% third-party, 0 ms blocking
Info::
Third-party code accounts for 2% of page weight (467.8 KiB of 19.9 MiB)
Info::
Third-party blocking time is low (0 ms)
98%
First-party Third-party
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
2 fonts (104 KB)
PASS
2 fonts (104 KB)
Info::
2 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

2

104 KB total

Render-blocking

0

of 2

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 5.2 s LCP 11.6 shttps://fonts.gstatic.com/s/montserrat/v31/JTUSjIg1_i6t8kCHKm459WlhyyTh89Y.woff2JTUSjIg1_i6t8kCHKm459Wl... https://fonts.gstatic.com/s/montserrat/v31/JTUSjIg1_i6t8kCHKm459WlhyyTh89Y.woff2 — 34.7 KiB — 54 ms — font-display: swaphttps://fonts.gstatic.com/s/heptaslab/v25/ea8cadoyU_jkHdalebHv42llhHCXA3A.woff2ea8cadoyU_jkHdalebHv42l... https://fonts.gstatic.com/s/heptaslab/v25/ea8cadoyU_jkHdalebHv42llhHCXA3A.woff2 — 68.9 KiB — 64 ms — font-display: swap
JTUSjIg1_i6t8kCHKm459Wl... woff2 swap
Size 35 KB
Load time 54 ms
Start 1.5 s
Risk FOUT — text flashes from fallback to web font
ea8cadoyU_jkHdalebHv42l... woff2 swap
Size 69 KB
Load time 64 ms
Start 1.5 s
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+
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
54 requests over 2958ms
INFO
0 ms 2.0 s 4.0 s 6.0 s 8.0 s 10.0 s 12.0 s FCP 5.2 s LCP 11.6 shttps://uci.edu// https://uci.edu/ — 200 — 140.3 KiB — 1.1 s — h2https://fonts.googleapis.com/css2?family=Roboto+Slab:wght@300;400;700&display=swapfonts.googleapis.com/css2?family=Ro... https://fonts.googleapis.com/css2?family=Roboto+Slab:wght@300;400;700&display=swap — 200 — 1.2 KiB — 102 ms — h2https://uci.edu/_assets/css/main.css/_assets/css/main.css https://uci.edu/_assets/css/main.css — 200 — 308.6 KiB — 691 ms — h2https://uci.edu/_assets/js/plugins/modernizr.js/_assets/js/plugins/modernizr.js https://uci.edu/_assets/js/plugins/modernizr.js — 200 — 5.7 KiB — 518 ms — h2https://cdnjs.cloudflare.com/ajax/libs/font-awesome/7.0.1/css/all.min.csscdnjs.cloudflare.com/ajax/libs/font... https://cdnjs.cloudflare.com/ajax/libs/font-awesome/7.0.1/css/all.min.css — 200 — 17.0 KiB — 94 ms — h2https://uci.edu/_assets/css/scpa-min.css/_assets/css/scpa-min.css https://uci.edu/_assets/css/scpa-min.css — 200 — 703 B — 517 ms — h2https://uci.edu/_assets/js/scpa-min.js/_assets/js/scpa-min.js https://uci.edu/_assets/js/scpa-min.js — 200 — 591 B — 340 ms — h2https://uci.edu/homepage/_imgs/video-loops/UC_Irvine_Homepage_Earth_Week_Video_Loop_Frame.jpg/homepage/_imgs/video-loops/UC_Irvi... https://uci.edu/homepage/_imgs/video-loops/UC_Irvine_Homepage_Earth_Week_Video_Loop_Frame.jpg — 200 — 799.2 KiB — 709 ms — h2https://uci.edu/_assets/img/home/research.png/_assets/img/home/research.png https://uci.edu/_assets/img/home/research.png — 200 — 110.8 KiB — 538 ms — h2https://fonts.googleapis.com/css2?family=Hepta+Slab:wght@1..900&family=Montserrat:ital,wght@0,100..900;1,100..900&display=swapfonts.googleapis.com/css2?family=He... https://fonts.googleapis.com/css2?family=Hepta+Slab:wght@1..900&family=Montserrat:ital,wght@0,100..900;1,100..900&display=swap — 200 — 838 B — 29 ms — h2https://uci.edu/homepage/_imgs/best-in-class.jpg/homepage/_imgs/best-in-class.jpg https://uci.edu/homepage/_imgs/best-in-class.jpg — 200 — 168.3 KiB — 195 ms — h2https://uci.edu/_assets/img/svg/decorative/UCI25-HPBA-Blue_Top-10.svg/_assets/img/svg/decorative/UCI25-H... https://uci.edu/_assets/img/svg/decorative/UCI25-HPBA-Blue_Top-10.svg — 200 — 5.4 KiB — 199 ms — h2https://uci.edu/_assets/img/svg/decorative/UCI25-HPBA-Blue_8B-econ.svg/_assets/img/svg/decorative/UCI25-H... https://uci.edu/_assets/img/svg/decorative/UCI25-HPBA-Blue_8B-econ.svg — 200 — 6.6 KiB — 198 ms — h2https://code.jquery.com/jquery-3.7.1.min.jscode.jquery.com/jquery-3.7.1.min.js https://code.jquery.com/jquery-3.7.1.min.js — 200 — 30.0 KiB — 37 ms — h2https://uci.edu/_assets/js/vendor.js/_assets/js/vendor.js https://uci.edu/_assets/js/vendor.js — 200 — 54.7 KiB — 195 ms — h2https://uci.edu/_assets/js/main.js/_assets/js/main.js https://uci.edu/_assets/js/main.js — 200 — 48.4 KiB — 200 ms — h2https://uci.edu/_assets/js/home.js/_assets/js/home.js https://uci.edu/_assets/js/home.js — 200 — 860 B — 314 ms — h2https://uci.edu/_assets/js/cookie-banner.js/_assets/js/cookie-banner.js https://uci.edu/_assets/js/cookie-banner.js — 200 — 1.1 KiB — 312 ms — h2https://www.googletagmanager.com/gtm.js?id=GTM-M2P2J94www.googletagmanager.com/gtm.js?id=... https://www.googletagmanager.com/gtm.js?id=GTM-M2P2J94 — 200 — 122.8 KiB — 154 ms — h2https://uci.edu/_assets/img/svg/decorative/UCI25-HPBA-Blue_best-value.svg/_assets/img/svg/decorative/UCI25-H... https://uci.edu/_assets/img/svg/decorative/UCI25-HPBA-Blue_best-value.svg — 200 — 4.8 KiB — 204 ms — h2https://uci.edu/_assets/img/svg/decorative/UCI25-HPBA-Blue_CMI-2.svg/_assets/img/svg/decorative/UCI25-H... https://uci.edu/_assets/img/svg/decorative/UCI25-HPBA-Blue_CMI-2.svg — 200 — 3.5 KiB — 200 ms — h2https://uci.edu/_assets/img/home/academics.jpg/_assets/img/home/academics.jpg https://uci.edu/_assets/img/home/academics.jpg — 200 — 48.0 KiB — 206 ms — h2https://uci.edu/_assets/img/home/admissions-and-aid.jpg/_assets/img/home/admissions-and-ai... https://uci.edu/_assets/img/home/admissions-and-aid.jpg — 200 — 63.7 KiB — 207 ms — h2https://uci.edu/_assets/img/home/campus-life.jpg/_assets/img/home/campus-life.jpg https://uci.edu/_assets/img/home/campus-life.jpg — 200 — 83.4 KiB — 313 ms — h2https://uci.edu/_assets/img/home/uci-health.jpg/_assets/img/home/uci-health.jpg https://uci.edu/_assets/img/home/uci-health.jpg — 200 — 112.1 KiB — 366 ms — h2https://uci.edu/_assets/img/home/samueli-college.jpg/_assets/img/home/samueli-college.j... https://uci.edu/_assets/img/home/samueli-college.jpg — 200 — 68.5 KiB — 391 ms — h2https://uci.edu/_assets/img/home/time-lapse.jpg/_assets/img/home/time-lapse.jpg https://uci.edu/_assets/img/home/time-lapse.jpg — 200 — 394.6 KiB — 374 ms — h2https://uci.edu/homepage/_imgs/community-background-arts.jpg/homepage/_imgs/community-backgroun... https://uci.edu/homepage/_imgs/community-background-arts.jpg — 200 — 323.7 KiB — 485 ms — h2https://uci.edu/_assets/img/home/community-arts.png/_assets/img/home/community-arts.pn... https://uci.edu/_assets/img/home/community-arts.png — 200 — 84.6 KiB — 549 ms — h2https://uci.edu/homepage/_imgs/community-background-athletics.jpg/homepage/_imgs/community-backgroun... https://uci.edu/homepage/_imgs/community-background-athletics.jpg — 200 — 372.7 KiB — 384 ms — h2
0 ms 2.0 s 4.0 s 6.0 s 8.0 s 10.0 s 12.0 s FCP 5.2 s LCP 11.6 shttps://uci.edu// https://uci.edu/ — 200 — 140.3 KiB — 1.1 s — h2https://fonts.googleapis.com/css2?family=Roboto+Slab:wght@300;400;700&display=swapfonts.googleapis.com/css2?family=Ro... https://fonts.googleapis.com/css2?family=Roboto+Slab:wght@300;400;700&display=swap — 200 — 1.2 KiB — 102 ms — h2https://uci.edu/_assets/css/main.css/_assets/css/main.css https://uci.edu/_assets/css/main.css — 200 — 308.6 KiB — 691 ms — h2https://uci.edu/_assets/js/plugins/modernizr.js/_assets/js/plugins/modernizr.js https://uci.edu/_assets/js/plugins/modernizr.js — 200 — 5.7 KiB — 518 ms — h2https://cdnjs.cloudflare.com/ajax/libs/font-awesome/7.0.1/css/all.min.csscdnjs.cloudflare.com/ajax/libs/font... https://cdnjs.cloudflare.com/ajax/libs/font-awesome/7.0.1/css/all.min.css — 200 — 17.0 KiB — 94 ms — h2https://uci.edu/_assets/css/scpa-min.css/_assets/css/scpa-min.css https://uci.edu/_assets/css/scpa-min.css — 200 — 703 B — 517 ms — h2https://uci.edu/_assets/js/scpa-min.js/_assets/js/scpa-min.js https://uci.edu/_assets/js/scpa-min.js — 200 — 591 B — 340 ms — h2https://uci.edu/homepage/_imgs/video-loops/UC_Irvine_Homepage_Earth_Week_Video_Loop_Frame.jpg/homepage/_imgs/video-loops/UC_Irvi... https://uci.edu/homepage/_imgs/video-loops/UC_Irvine_Homepage_Earth_Week_Video_Loop_Frame.jpg — 200 — 799.2 KiB — 709 ms — h2https://uci.edu/_assets/img/home/research.png/_assets/img/home/research.png https://uci.edu/_assets/img/home/research.png — 200 — 110.8 KiB — 538 ms — h2https://fonts.googleapis.com/css2?family=Hepta+Slab:wght@1..900&family=Montserrat:ital,wght@0,100..900;1,100..900&display=swapfonts.googleapis.com/css2?family=He... https://fonts.googleapis.com/css2?family=Hepta+Slab:wght@1..900&family=Montserrat:ital,wght@0,100..900;1,100..900&display=swap — 200 — 838 B — 29 ms — h2https://uci.edu/homepage/_imgs/best-in-class.jpg/homepage/_imgs/best-in-class.jpg https://uci.edu/homepage/_imgs/best-in-class.jpg — 200 — 168.3 KiB — 195 ms — h2https://uci.edu/_assets/img/svg/decorative/UCI25-HPBA-Blue_Top-10.svg/_assets/img/svg/decorative/UCI25-H... https://uci.edu/_assets/img/svg/decorative/UCI25-HPBA-Blue_Top-10.svg — 200 — 5.4 KiB — 199 ms — h2https://uci.edu/_assets/img/svg/decorative/UCI25-HPBA-Blue_8B-econ.svg/_assets/img/svg/decorative/UCI25-H... https://uci.edu/_assets/img/svg/decorative/UCI25-HPBA-Blue_8B-econ.svg — 200 — 6.6 KiB — 198 ms — h2https://code.jquery.com/jquery-3.7.1.min.jscode.jquery.com/jquery-3.7.1.min.js https://code.jquery.com/jquery-3.7.1.min.js — 200 — 30.0 KiB — 37 ms — h2https://uci.edu/_assets/js/vendor.js/_assets/js/vendor.js https://uci.edu/_assets/js/vendor.js — 200 — 54.7 KiB — 195 ms — h2https://uci.edu/_assets/js/main.js/_assets/js/main.js https://uci.edu/_assets/js/main.js — 200 — 48.4 KiB — 200 ms — h2https://uci.edu/_assets/js/home.js/_assets/js/home.js https://uci.edu/_assets/js/home.js — 200 — 860 B — 314 ms — h2https://uci.edu/_assets/js/cookie-banner.js/_assets/js/cookie-banner.js https://uci.edu/_assets/js/cookie-banner.js — 200 — 1.1 KiB — 312 ms — h2https://www.googletagmanager.com/gtm.js?id=GTM-M2P2J94www.googletagmanager.com/gtm.js?id=... https://www.googletagmanager.com/gtm.js?id=GTM-M2P2J94 — 200 — 122.8 KiB — 154 ms — h2https://uci.edu/_assets/img/svg/decorative/UCI25-HPBA-Blue_best-value.svg/_assets/img/svg/decorative/UCI25-H... https://uci.edu/_assets/img/svg/decorative/UCI25-HPBA-Blue_best-value.svg — 200 — 4.8 KiB — 204 ms — h2https://uci.edu/_assets/img/svg/decorative/UCI25-HPBA-Blue_CMI-2.svg/_assets/img/svg/decorative/UCI25-H... https://uci.edu/_assets/img/svg/decorative/UCI25-HPBA-Blue_CMI-2.svg — 200 — 3.5 KiB — 200 ms — h2https://uci.edu/_assets/img/home/academics.jpg/_assets/img/home/academics.jpg https://uci.edu/_assets/img/home/academics.jpg — 200 — 48.0 KiB — 206 ms — h2https://uci.edu/_assets/img/home/admissions-and-aid.jpg/_assets/img/home/admissions-and-ai... https://uci.edu/_assets/img/home/admissions-and-aid.jpg — 200 — 63.7 KiB — 207 ms — h2https://uci.edu/_assets/img/home/campus-life.jpg/_assets/img/home/campus-life.jpg https://uci.edu/_assets/img/home/campus-life.jpg — 200 — 83.4 KiB — 313 ms — h2https://uci.edu/_assets/img/home/uci-health.jpg/_assets/img/home/uci-health.jpg https://uci.edu/_assets/img/home/uci-health.jpg — 200 — 112.1 KiB — 366 ms — h2https://uci.edu/_assets/img/home/samueli-college.jpg/_assets/img/home/samueli-college.j... https://uci.edu/_assets/img/home/samueli-college.jpg — 200 — 68.5 KiB — 391 ms — h2https://uci.edu/_assets/img/home/time-lapse.jpg/_assets/img/home/time-lapse.jpg https://uci.edu/_assets/img/home/time-lapse.jpg — 200 — 394.6 KiB — 374 ms — h2https://uci.edu/homepage/_imgs/community-background-arts.jpg/homepage/_imgs/community-backgroun... https://uci.edu/homepage/_imgs/community-background-arts.jpg — 200 — 323.7 KiB — 485 ms — h2https://uci.edu/_assets/img/home/community-arts.png/_assets/img/home/community-arts.pn... https://uci.edu/_assets/img/home/community-arts.png — 200 — 84.6 KiB — 549 ms — h2https://uci.edu/homepage/_imgs/community-background-athletics.jpg/homepage/_imgs/community-backgroun... https://uci.edu/homepage/_imgs/community-background-athletics.jpg — 200 — 372.7 KiB — 384 ms — h2https://uci.edu/_assets/img/home/community-athletics.png/_assets/img/home/community-athleti... https://uci.edu/_assets/img/home/community-athletics.png — 200 — 110.0 KiB — 549 ms — h2https://uci.edu/_assets/img/home/visit-01.jpg/_assets/img/home/visit-01.jpg https://uci.edu/_assets/img/home/visit-01.jpg — 200 — 648.6 KiB — 548 ms — h2https://uci.edu/_assets/img/home/visit-02.jpg/_assets/img/home/visit-02.jpg https://uci.edu/_assets/img/home/visit-02.jpg — 200 — 584.4 KiB — 595 ms — h2https://uci.edu/homepage/_imgs/visit-04.jpg/homepage/_imgs/visit-04.jpg https://uci.edu/homepage/_imgs/visit-04.jpg — 200 — 662.7 KiB — 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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
59% of JavaScript execution is third-party
First-party Third-party 1525ms · 315KB · $20/mo
Unattributable
Other
Costly
Execution 1052ms
Transfer 0 KB
Monthly Cost $14/mo
Google Tag Manager
Tag Manager
Optional
Execution 175ms
Transfer 123 KB
Unused 53%
Monthly Cost $2/mo
Google Tag Manager
Tag Manager
Optional
Execution 169ms
Transfer 151 KB
Unused 43%
Monthly Cost $2/mo
siteimproveanalytics.com
Other
Optional
Execution 129ms
Transfer 41 KB
Monthly Cost $2/mo

These scripts may cost more than they're worth

  • Unattributable adds 1052ms and costs ~$14/month

59% 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.

Learn more ▾

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 1052ms 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

53% of Google Tag Manager'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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