Performance
· 17 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.Performance-focused optimization plan with CWV assessment, top offenders, and time estimates
First Contentful Paint First Contentful Paint — how long until the browser renders the first piece of content. Under 1.8s is good.
5.32 s
Largest Contentful Paint Largest Contentful Paint — how long until the largest visible element loads. Under 2.5s is good.
14.49 s
Total Blocking Time Total Blocking Time — total time the main thread was blocked, preventing user input. Under 200ms is good.
775 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.
9.46 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.
21.28 s
Page Load Progression
FPage Weight BudgetAction5.4 MB transferred, 108 requestsFIX
Convert images to WebP/AVIF and resize to display dimensions to reduce transfer size.
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.
JavaScript bundle is large — code-split routes and lazy-load off-screen components to defer.
Source: web.dev
Subset fonts to include only used characters, or switch to system font stacks.
Font payload is large — subset to used glyphs only, or fall back to system fonts (zero load time).
Source: web.dev font loading
Each request adds latency. Bundle small files, use sprites, or eliminate unnecessary requests.
High HTTP request count — bundling, sprite-ing, and HTTP/2 server push can reduce per-request overhead.
Source: web.dev
DThird-Party ImpactAction100% third-party, 0 ms blockingFIX
FJS Execution CostAction4950ms total JS executionFIX
Main Thread Breakdown
| Script | Total | Scripting | Parse/Compile | Party |
|---|---|---|---|---|
| https://www.cmu.edu/ | 1195ms | 11ms | 2ms | 3rd |
| Unattributable | 1044ms | 177ms | 0ms | 3rd |
| https://www.googletagmanager.com/gtm.js?id=GTM-5Q36JQ | 445ms | 358ms | 49ms | 3rd |
| https://www.googletagmanager.com/gtag/destination?id=AW-10975680821&cx=c>m=4e64h1 | 362ms | 313ms | 45ms | 3rd |
| https://scripts.clarity.ms/0.8.59/clarity.js | 349ms | 314ms | 9ms | 3rd |
| https://cdn.cookielaw.org/scripttemplates/202511.1.0/otBannerSdk.js | 276ms | 199ms | 40ms | 3rd |
| https://events.cmu.edu/live/resource/js/%5Clivewhale%5Cthirdparty%5Cjquery%5Cjquery.no-conflict-header.js/%5Clivewhale%5Cthirdparty%5Cjquery%5Cjquery.js/%5Clivewhale%5Cthirdparty%5Cjquery%5Cjquery.no-conflict-footer.js/%5Clivewhale%5Cscripts%5Clib%5Cdate%5Cformatter.js/%5Clivewhale%5Cscripts%5Clib%5Cdate%5Ctimezone.js/%5Clivewhale%5Cscripts%5Clib%5Cdate%5Cuser.js/%5Clivewhale%5Cplugins%5Cjquery%5Cjquery.lw-widget.js | 259ms | 113ms | 13ms | 3rd |
| https://www.googletagmanager.com/gtag/js?id=G-1XQYSMEBVE&cx=c>m=4e64h1 | 251ms | 174ms | 47ms | 3rd |
| https://resources.usersnap.com/widget-assets/js/entries/globalSetup/8fa14b1d6833454c.js | 198ms | 163ms | 32ms | 3rd |
| https://www.cmu.edu/themes/custom/cmu_base/dist/assets/script.js?v=11.3.5 | 191ms | 47ms | 0ms | 3rd |
Showing top 10 of 14 scripts
DJS BundlesAction35 scripts, 408 KB unusedFIX
Downloaded but never executed on this page.
| Script | Size | Unused | Minified | Party |
|---|---|---|---|---|
| https://cdn.cookielaw.org/scripttemplates/202511.1.0/otBannerSdk.js | 124 KB | 69 KB (56%) | ✓ | 3rd |
| https://www.googletagmanager.com/gtag/js?id=G-1XQYSMEBVE&cx=c>m=4e64h1 | 175 KB | 67 KB (39%) | ✓ | 3rd |
| https://www.googletagmanager.com/gtag/destination?id=AW-10975680821&cx=c>m=4e64h1 | 145 KB | 59 KB (41%) | ✓ | 3rd |
| https://www.googletagmanager.com/gtm.js?id=GTM-5Q36JQ | 180 KB | 56 KB (31%) | ✓ | 3rd |
| https://www.google.com/cse/static/element/b33cba5881f68fbf/cse_element__en.js?usqp=CAI%3D | 98 KB | 49 KB (50%) | ✓ | 3rd |
| https://cse.google.com/adsense/search/async-ads.js | 44 KB | 32 KB (73%) | ✓ | 3rd |
| https://resources.usersnap.com/widget-assets/js/entries/globalSetup/8fa14b1d6833454c.js | 72 KB | 29 KB (40%) | ✓ | 3rd |
| https://www.cmu.edu/core/assets/vendor/jquery/jquery.min.js?v=4.0.0 | 35 KB | 25 KB (73%) | ✓ | 3rd |
| https://www.cmu.edu/themes/custom/cmu_base/dist/assets/script2.js | 32 KB | 21 KB (67%) | ✗ | 3rd |
| https://cdn.cookielaw.org/scripttemplates/otSDKStub.js?did=019aea8f-3cc9-711f-bb14-1f9a6341eb66 | 9 KB | — | ✓ | 3rd |
Consider code splitting or tree shaking to reduce unused code.
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.
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.
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.
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.
This bundle has high unused code — code-split or tree-shake to ship only what executes.
Source: web.dev / Lighthouse coverage
FPage Weight InventoryAction108 resources · 5.4 MB · 408 KB savings availableFIX
~407.6 KiB of savings available
| # | Resource | Type | Size | Cache | Unused | 3rd party | Issues |
|---|---|---|---|---|---|---|---|
| — | — | ||||||
| 108 resources | 5.4 MiB | ||||||
FHTTP CachingActionNo cache headersFIX
No Cache-Control header
Adding a Cache-Control header can significantly improve repeat-visit performance.
BImage Optimization30 images, 0 KB saveableREVIEW
CGreen HostingActionWhether the site is served from green-energy infrastructureREVIEW
Green Hosting
No green hosting detected
A+Text CompressionAll text resources are compressedPASS
A+Font Loading6 fonts (218 KB)PASS
Web fonts
6
218 KB total
Render-blocking
0
of 6
Dominant font-display
swap
Most common across fonts
Font loading timeline
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 CachingAll resources properly cachedPASS
A+Critical Rendering PathNo render-blocking resourcesPASS
A+Resource HintsNo optimization neededPASS
A+Render-Blocking ResourcesNo render-blocking resources detectedPASS
A+Third-Party ResourcesNo third-party resources detectedPASS
Network Waterfall108 requests over 6272msINFO
Third-Party Script CostPer-script blocking time, transfer cost, and cache headersINFO
| Script | Category | Execution | Transfer | Unused | Monthly Cost | Verdict |
|---|---|---|---|---|---|---|
www.cmu.edu www.cmu.edu | Other | 1195ms | 29 KB | — | $16/mo | Costly |
Unattributable Unattributable | Other | 1044ms | 0 KB | — | $14/mo | Costly |
Google Tag Manager www.googletagmanager.com | Tag Manager | 445ms | 180 KB | 31% | $6/mo | Costly |
Google Tag Manager www.googletagmanager.com | Tag Manager | 362ms | 145 KB | 41% | $5/mo | Costly |
Microsoft Clarity scripts.clarity.ms | Session Replay | 349ms | 26 KB | — | $5/mo | Costly |
OneTrust cdn.cookielaw.org | Consent | 276ms | 124 KB | 56% | $4/mo | Essential |
events.cmu.edu events.cmu.edu | Other | 259ms | 36 KB | — | $3/mo | Costly |
Google Tag Manager www.googletagmanager.com | Tag Manager | 251ms | 175 KB | 39% | $3/mo | Costly |
resources.usersnap.com resources.usersnap.com | Other | 198ms | 72 KB | 40% | $3/mo | Optional |
www.cmu.edu www.cmu.edu | Other | 191ms | 13 KB | — | $3/mo | Optional |
cse.google.com cse.google.com | Other | 139ms | 4 KB | — | $2/mo | Optional |
ep2.adtrafficquality.google ep2.adtrafficquality.google | Other | 128ms | 8 KB | — | $2/mo | Optional |
cse.google.com cse.google.com | Other | 58ms | 44 KB | 73% | $1/mo | Optional |
www.google.com www.google.com | Other | 56ms | 98 KB | 50% | $1/mo | Optional |
These scripts may cost more than they're worth
- www.cmu.edu adds 1195ms and costs ~$16/month
- Unattributable adds 1044ms and costs ~$14/month
- Google Tag Manager adds 445ms and costs ~$6/month
- Google Tag Manager adds 362ms and costs ~$5/month
- Microsoft Clarity adds 349ms and costs ~$5/month
- events.cmu.edu adds 259ms and costs ~$3/month
- Google Tag Manager adds 251ms and costs ~$3/month
100% of JavaScript execution time is spent on third-party scripts. Consider auditing which scripts are essential.
When third-party JS execution time exceeds your own, performance gains from frontend work are capped by code you don't own.
Learn more ▾ ▴
Every millisecond of third-party JS competes with your own for main-thread time. If their share is bigger than yours, optimization on your code base barely moves the needle. Audit, defer, or remove third-parties before further frontend optimization. Use Lighthouse's third-party audit to identify the worst offenders.
Source: web.dev
www.cmu.edu takes 1195ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
Unattributable takes 1044ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
Google Tag Manager takes 445ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
Google Tag Manager takes 362ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
Microsoft Clarity takes 349ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
56% of OneTrust's code is unused. The script may be loading features you don't use.
Bundle has high unused-code ratio — tree-shaking and route-splitting recover the wasted bytes.
Source: web.dev
events.cmu.edu takes 259ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
Google Tag Manager takes 251ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
73% of cse.google.com's code is unused. The script may be loading features you don't use.
Bundle has high unused-code ratio — tree-shaking and route-splitting recover the wasted bytes.
Source: web.dev