Performance
· 15 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.
2.93 s
Largest Contentful Paint Largest Contentful Paint — how long until the largest visible element loads. Under 2.5s is good.
5.36 s
Total Blocking Time Total Blocking Time — total time the main thread was blocked, preventing user input. Under 200ms is good.
86 ms
Cumulative Layout Shift Cumulative Layout Shift — measures visual stability. How much the page layout shifts during loading. Under 0.1 is good.
0.074
Speed Index Speed Index — how quickly content is visually displayed during load. Under 3.4s is good.
4.32 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.
5.42 s
Page Load Progression
FPage Weight BudgetAction5.3 MB transferred, 77 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
DThird-Party ImpactAction100% third-party, 0 ms blockingFIX
DPage Weight InventoryAction77 resources · 5.3 MB · 253 KB savings availableFIX
~252.9 KiB of savings available
| # | Resource | Type | Size | Cache | Unused | 3rd party | Issues |
|---|---|---|---|---|---|---|---|
| — | — | ||||||
| 77 resources | 5.3 MiB | ||||||
FHTTP CachingActionNo cache headersFIX
No Cache-Control header
Adding a Cache-Control header can significantly improve repeat-visit performance.
BImage Optimization28 images, 0 KB saveableREVIEW
BJS Execution Cost807ms total JS executionREVIEW
Main Thread Breakdown
| Script | Total | Scripting | Parse/Compile | Party |
|---|---|---|---|---|
| https://www.rochester.edu/ | 219ms | 8ms | 1ms | 3rd |
| Unattributable | 218ms | 16ms | 0ms | 3rd |
| https://www.googletagmanager.com/gtag/js?id=G-NLJHQXH6R7&cx=c>m=4e64h1 | 122ms | 95ms | 26ms | 3rd |
| https://www.googletagmanager.com/gtm.js?id=GTM-TT7PP8Z | 110ms | 88ms | 17ms | 3rd |
| https://www.googletagmanager.com/gtag/js?id=AW-16785116022&cx=c>m=4e64h1 | 83ms | 69ms | 13ms | 3rd |
| https://connect.facebook.net/signals/config/3883923348587710?v=2.9.303&r=stable&domain=www.rochester.edu&hme=97937018cefade17726f0472876fc101316b2ce9008a35a6a5a7977d7436151a&ex_m=104%2C205%2C154%2C22%2C72%2C73%2C145%2C68%2C67%2C11%2C162%2C90%2C16%2C138%2C127%2C39%2C75%2C78%2C134%2C159%2C164%2C8%2C4%2C5%2C7%2C6%2C3%2C91%2C101%2C165%2C170%2C219%2C62%2C186%2C187%2C55%2C276%2C30%2C74%2C231%2C230%2C229%2C23%2C33%2C103%2C61%2C10%2C63%2C97%2C98%2C99%2C105%2C130%2C31%2C29%2C132%2C133%2C129%2C128%2C155%2C76%2C158%2C156%2C157%2C50%2C60%2C123%2C15%2C161%2C45%2C263%2C264%2C262%2C26%2C27%2C28%2C48%2C146%2C77%2C112%2C18%2C20%2C44%2C40%2C42%2C41%2C83%2C92%2C96%2C110%2C144%2C147%2C46%2C111%2C24%2C21%2C119%2C69%2C36%2C149%2C148%2C150%2C141%2C139%2C25%2C35%2C59%2C109%2C160%2C70%2C17%2C152%2C114%2C81%2C66%2C19%2C85%2C86%2C116%2C84%2C136%2C135%2C34%2C278%2C293%2C212%2C201%2C202%2C200%2C296%2C288%2C52%2C213%2C107%2C131%2C80%2C121%2C54%2C47%2C49%2C113%2C120%2C126%2C58%2C64%2C151%2C115%2C37%2C32%2C53%2C56%2C100%2C163%2C1%2C124%2C14%2C122%2C12%2C2%2C57%2C93%2C65%2C118%2C89%2C88%2C166%2C167%2C94%2C95%2C9%2C125%2C102%2C51%2C142%2C87%2C79%2C71%2C117%2C106%2C43%2C143%2C0%2C82%2C137%2C140%2C153%2C38%2C108%2C13%2C168 | 56ms | 45ms | 9ms | 3rd |
CJS BundlesAction13 scripts, 253 KB unusedREVIEW
Downloaded but never executed on this page.
| Script | Size | Unused | Minified | Party |
|---|---|---|---|---|
| https://www.googletagmanager.com/gtm.js?id=GTM-TT7PP8Z | 154 KB | 74 KB (48%) | ✓ | 3rd |
| https://www.googletagmanager.com/gtag/js?id=G-NLJHQXH6R7&cx=c>m=4e64h1 | 176 KB | 70 KB (40%) | ✓ | 3rd |
| https://www.googletagmanager.com/gtag/js?id=AW-16785116022&cx=c>m=4e64h1 | 138 KB | 54 KB (39%) | ✓ | 3rd |
| https://connect.facebook.net/en_US/fbevents.js | 97 KB | 33 KB (35%) | ✓ | 3rd |
| https://www.rochester.edu/templatefiles/2025/js/main.min.js | 30 KB | 21 KB (72%) | ✓ | 3rd |
| https://bat.bing.com/bat.js | 15 KB | — | ✓ | 3rd |
| https://kit.fontawesome.com/09cf01df45.js | 6 KB | — | ✓ | 3rd |
| https://sc-static.net/scevent.min.js | 25 KB | — | ✓ | 3rd |
| https://googleads.g.doubleclick.net/pagead/viewthroughconversion/16785116022/?random=1776801986032&cv=11&fst=1776801986032&bg=ffffff&guid=ON&async=1&en=gtag.config>m=45be64h1v9201859962z8813410015za20gzb813410015zd813410015xec&gcd=13l3l3l3l1l1&dma=0&tag_exp=0~115938466~115938468~117266401&u_w=800&u_h=600&url=https%3A%2F%2Fwww.rochester.edu%2F&rcb=13&frm=0&tiba=University%20of%20Rochester%20%7C%20Where%20Wonder%20Fuels%20Discovery&hn=www.googleadservices.com&npa=0&pscdl=noapi&auid=394055250.1776801986&uaa=x86&uab=64&uafvl=Not-A.Brand%3B24.0.0.0%7CChromium%3B146.0.7680.164&uamb=0&uam=&uap=macOS&uapv=10.15.7&uaw=0&data=event%3Dgtag.config&rfmt=3&fmt=4 | 2 KB | — | ✓ | 3rd |
| https://connect.facebook.net/signals/config/3883923348587710?v=2.9.303&r=stable&domain=www.rochester.edu&hme=97937018cefade17726f0472876fc101316b2ce9008a35a6a5a7977d7436151a&ex_m=104%2C205%2C154%2C22%2C72%2C73%2C145%2C68%2C67%2C11%2C162%2C90%2C16%2C138%2C127%2C39%2C75%2C78%2C134%2C159%2C164%2C8%2C4%2C5%2C7%2C6%2C3%2C91%2C101%2C165%2C170%2C219%2C62%2C186%2C187%2C55%2C276%2C30%2C74%2C231%2C230%2C229%2C23%2C33%2C103%2C61%2C10%2C63%2C97%2C98%2C99%2C105%2C130%2C31%2C29%2C132%2C133%2C129%2C128%2C155%2C76%2C158%2C156%2C157%2C50%2C60%2C123%2C15%2C161%2C45%2C263%2C264%2C262%2C26%2C27%2C28%2C48%2C146%2C77%2C112%2C18%2C20%2C44%2C40%2C42%2C41%2C83%2C92%2C96%2C110%2C144%2C147%2C46%2C111%2C24%2C21%2C119%2C69%2C36%2C149%2C148%2C150%2C141%2C139%2C25%2C35%2C59%2C109%2C160%2C70%2C17%2C152%2C114%2C81%2C66%2C19%2C85%2C86%2C116%2C84%2C136%2C135%2C34%2C278%2C293%2C212%2C201%2C202%2C200%2C296%2C288%2C52%2C213%2C107%2C131%2C80%2C121%2C54%2C47%2C49%2C113%2C120%2C126%2C58%2C64%2C151%2C115%2C37%2C32%2C53%2C56%2C100%2C163%2C1%2C124%2C14%2C122%2C12%2C2%2C57%2C93%2C65%2C118%2C89%2C88%2C166%2C167%2C94%2C95%2C9%2C125%2C102%2C51%2C142%2C87%2C79%2C71%2C117%2C106%2C43%2C143%2C0%2C82%2C137%2C140%2C153%2C38%2C108%2C13%2C168 | 46 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
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 Loading12 fonts (294 KB)PASS
Web fonts
12
294 KB total
Render-blocking
0
of 12
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
Network Waterfall77 requests over 8307msINFO
Third-Party Script CostPer-script blocking time, transfer cost, and cache headersINFO
| Script | Category | Execution | Transfer | Unused | Monthly Cost | Verdict |
|---|---|---|---|---|---|---|
www.rochester.edu www.rochester.edu | Other | 219ms | 11 KB | — | $3/mo | Costly |
Unattributable Unattributable | Other | 218ms | 0 KB | — | $3/mo | Costly |
Google Tag Manager www.googletagmanager.com | Tag Manager | 122ms | 176 KB | 40% | $2/mo | Optional |
Google Tag Manager www.googletagmanager.com | Tag Manager | 110ms | 154 KB | 48% | $1/mo | Optional |
Google Tag Manager www.googletagmanager.com | Tag Manager | 83ms | 138 KB | 39% | $1/mo | Optional |
Facebook Pixel connect.facebook.net | Advertising | 56ms | 46 KB | — | $1/mo | Optional |
These scripts may cost more than they're worth
- www.rochester.edu adds 219ms and costs ~$3/month
- Unattributable adds 218ms 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.rochester.edu takes 219ms 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 218ms 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