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.
3.74 s
Largest Contentful Paint Largest Contentful Paint — how long until the largest visible element loads. Under 2.5s is good.
20.52 s
Total Blocking Time Total Blocking Time — total time the main thread was blocked, preventing user input. Under 200ms is good.
165 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.
6.49 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.
20.65 s
Page Load Progression
FPage Weight BudgetAction7.7 MB transferred, 87 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
DThird-Party ImpactAction100% third-party, 0 ms blockingFIX
DPage Weight InventoryAction87 resources · 7.7 MB · 214 KB savings availableFIX
~214.1 KiB of savings available
| # | Resource | Type | Size | Cache | Unused | 3rd party | Issues |
|---|---|---|---|---|---|---|---|
| — | — | ||||||
| 87 resources | 7.7 MiB | ||||||
FHTTP CachingActionNo cache headersFIX
No Cache-Control header
Adding a Cache-Control header can significantly improve repeat-visit performance.
CImage OptimizationAction30 images, 0 KB saveableREVIEW
Set explicit width and height to prevent CLS.
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.
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.
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.
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.
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.
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.
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.
Image without explicit width/height — browser can't reserve space; CLS jumps when image loads.
Source: web.dev / Core Web Vitals
CJS Execution CostAction1607ms total JS executionREVIEW
Main Thread Breakdown
| Script | Total | Scripting | Parse/Compile | Party |
|---|---|---|---|---|
| Unattributable | 584ms | 15ms | 0ms | 3rd |
| https://washu.edu/ | 495ms | 9ms | 4ms | 3rd |
| https://www.googletagmanager.com/gtag/js?id=GT-5RF8WH5 | 212ms | 177ms | 33ms | 3rd |
| https://www.googletagmanager.com/gtm.js?id=GTM-TXV3L6Q | 152ms | 118ms | 34ms | 3rd |
| https://washu.edu/app/plugins/washu-cludo-functionality//cludo-config/dist/js/cludo-search-results.js?ver=1.0.3 | 86ms | 66ms | 19ms | 3rd |
| https://washu.edu/app/themes/antipasto/build/scripts.js?ver=4.0.45 | 77ms | 16ms | 2ms | 3rd |
CJS BundlesAction18 scripts, 214 KB unusedREVIEW
Downloaded but never executed on this page.
| Script | Size | Unused | Minified | Party |
|---|---|---|---|---|
| https://www.googletagmanager.com/gtm.js?id=GTM-TXV3L6Q | 131 KB | 67 KB (52%) | ✓ | 3rd |
| https://www.googletagmanager.com/gtag/js?id=GT-5RF8WH5 | 157 KB | 65 KB (41%) | ✓ | 3rd |
| https://washu.edu/app/plugins/washu-cludo-functionality//cludo-config/dist/js/cludo-search-results.js?ver=1.0.3 | 88 KB | 57 KB (64%) | ✓ | 3rd |
| https://customer.cludo.com/scripts/bundles/search-script.min.js?ver=1.0.3 | 51 KB | 25 KB (51%) | ✓ | 3rd |
| https://washu.edu/app/themes/washuedu-theme/build/script-story-carousel.js?ver=e36bc714e21d6a96886e | 1 KB | — | ✓ | 3rd |
| https://washu.edu/app/themes/washuedu-theme/build/script-small-photo-promo.js?ver=1.0.38 | 4 KB | — | ✓ | 3rd |
| https://washu.edu/wp/wp-includes/js/dist/dom-ready.min.js?ver=f77871ff7694fffea381 | 1 KB | — | ✓ | 3rd |
| https://washu.edu/app/themes/washuedu-theme/build/script-video-topper.js?ver=4.0.45 | 1 KB | — | ✓ | 3rd |
| https://washu.edu/app/plugins/washu-emergency-alerts/js/washu-emergency-alerts.js?ver=1.5.3 | 1 KB | — | ✓ | 3rd |
| https://washu.edu/app/themes/washuedu-theme/build/script-flag-half-staff.js?ver=eb92675966cf04e5ddd8 | 1 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
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 (133 KB)PASS
Web fonts
6
133 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 Hints5 hints, 0 missing preconnectsPASS
Current Resource Hints
5 resource hints configured
A+Render-Blocking ResourcesNo render-blocking resources detectedPASS
A+Third-Party ResourcesNo third-party resources detectedPASS
Network Waterfall87 requests over 2149msINFO
Third-Party Script CostPer-script blocking time, transfer cost, and cache headersINFO
| Script | Category | Execution | Transfer | Unused | Monthly Cost | Verdict |
|---|---|---|---|---|---|---|
Unattributable Unattributable | Other | 584ms | 0 KB | — | $8/mo | Costly |
washu.edu washu.edu | Other | 495ms | 35 KB | — | $7/mo | Costly |
Google Tag Manager www.googletagmanager.com | Tag Manager | 212ms | 157 KB | 41% | $3/mo | Costly |
Google Tag Manager www.googletagmanager.com | Tag Manager | 152ms | 131 KB | 52% | $2/mo | Optional |
washu.edu washu.edu | Other | 86ms | 88 KB | 64% | $1/mo | Optional |
washu.edu washu.edu | Other | 77ms | 6 KB | — | $1/mo | Optional |
These scripts may cost more than they're worth
- Unattributable adds 584ms and costs ~$8/month
- washu.edu adds 495ms and costs ~$7/month
- Google Tag Manager adds 212ms 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
Unattributable takes 584ms 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
washu.edu takes 495ms 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 212ms 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
52% of Google Tag Manager'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
64% of washu.edu'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