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.
3.90 s
Largest Contentful Paint Largest Contentful Paint — how long until the largest visible element loads. Under 2.5s is good.
21.66 s
Total Blocking Time Total Blocking Time — total time the main thread was blocked, preventing user input. Under 200ms is good.
1.01 s
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.
6.37 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.
22.00 s
Page Load Progression
FPage Weight BudgetAction7.1 MB transferred, 82 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
FJS Execution CostAction4336ms total JS executionFIX
Main Thread Breakdown
| Script | Total | Scripting | Parse/Compile | Party |
|---|---|---|---|---|
| https://www.brown.edu/sites/default/files/js/js_DOECIYZkPn1B_8vq27gBC0SjwsM3Nj_H45TcFSoooss.js?scope=footer&delta=0&language=en&theme=brown&include=eJxlyrENwCAMBMCFUBjJMggcI8NHGJT1Q5_iumP3skhHK3lhxuaXgQQQK_T4MdFB6949DVYL_PtnVD27Im8PaeIdUQyJ7QO6_STM | 1700ms | 715ms | 21ms | 3rd |
| https://www.brown.edu/ | 1017ms | 9ms | 2ms | 3rd |
| Unattributable | 414ms | 9ms | 0ms | 3rd |
| https://www.googletagmanager.com/gtm.js?id=GTM-KX5NV9 | 397ms | 339ms | 48ms | 3rd |
| https://www.googletagmanager.com/gtag/js?id=G-PCH3TG4K4L&cx=c>m=4e64k0h2 | 273ms | 217ms | 55ms | 3rd |
| https://www.googletagmanager.com/gtag/js?id=G-S0MX9K9C18&cx=c>m=4e64k0h2 | 241ms | 200ms | 39ms | 3rd |
| https://www.googletagmanager.com/gtag/js?id=G-QY13L4Q0C0&cx=c>m=4e64k0h2 | 234ms | 188ms | 44ms | 3rd |
| https://www.brown.edu/sites/default/files/css/css_8vgz6odbIwqY9EZIoh6i9uF5WomfkgX634vfPlKkLxU.css?delta=1&language=en&theme=brown&include=eJx1jDsSwjAMBS_kiVNxHY0Si9igWBrJ-d0eJhQUkPbt7kN3alDqg8YmFkf3ru8hy0yw3gL-UhbAOmYx4FKffqFkBdqVxWgw2Srkkgic-JQuGsWWoeH-D-sMnyOWlRzUZH0_1pEuZMUDSoO72IaWIOERzj5OLANyUDScDDV7TLYocvdduqXqMnDxTCn44Y3mOKDTCzfhdms | 60ms | 0ms | 0ms | 3rd |
DJS BundlesAction6 scripts, 310 KB unusedFIX
Downloaded but never executed on this page.
| Script | Size | Unused | Minified | Party |
|---|---|---|---|---|
| https://www.googletagmanager.com/gtag/js?id=G-QY13L4Q0C0&cx=c>m=4e64k0h2 | 173 KB | 73 KB (42%) | ✓ | 3rd |
| https://www.googletagmanager.com/gtag/js?id=G-PCH3TG4K4L&cx=c>m=4e64k0h2 | 173 KB | 73 KB (42%) | ✓ | 3rd |
| https://www.googletagmanager.com/gtag/js?id=G-S0MX9K9C18&cx=c>m=4e64k0h2 | 152 KB | 64 KB (42%) | ✓ | 3rd |
| https://www.googletagmanager.com/gtm.js?id=GTM-KX5NV9 | 174 KB | 57 KB (33%) | ✓ | 3rd |
| https://www.brown.edu/sites/default/files/js/js_DOECIYZkPn1B_8vq27gBC0SjwsM3Nj_H45TcFSoooss.js?scope=footer&delta=0&language=en&theme=brown&include=eJxlyrENwCAMBMCFUBjJMggcI8NHGJT1Q5_iumP3skhHK3lhxuaXgQQQK_T4MdFB6949DVYL_PtnVD27Im8PaeIdUQyJ7QO6_STM | 83 KB | 43 KB (53%) | ✓ | 3rd |
| https://extend.vimeocdn.com/ga/2806066.js | 6 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
DPage Weight InventoryAction82 resources · 7.1 MB · 310 KB savings availableFIX
~309.7 KiB of savings available
| # | Resource | Type | Size | Cache | Unused | 3rd party | Issues |
|---|---|---|---|---|---|---|---|
| — | — | ||||||
| 82 resources | 7.1 MiB | ||||||
FHTTP CachingActionNo cache headersFIX
No Cache-Control header
Adding a Cache-Control header can significantly improve repeat-visit performance.
BImage Optimization52 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
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 (307 KB)PASS
Web fonts
6
307 KB total
Render-blocking
0
of 6
Dominant font-display
swap
Most common across fonts
Font loading timeline
- Convert to woff2 for ~30% smaller file size
- Convert to woff2 for ~30% smaller file size
- Convert to woff2 for ~30% smaller file size
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 ~37 KB and ~74 ms
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 Waterfall82 requests over 1469msINFO
Third-Party Script CostPer-script blocking time, transfer cost, and cache headersINFO
| Script | Category | Execution | Transfer | Unused | Monthly Cost | Verdict |
|---|---|---|---|---|---|---|
www.brown.edu www.brown.edu | Other | 1700ms | 83 KB | 53% | $23/mo | Costly |
www.brown.edu www.brown.edu | Other | 1017ms | 19 KB | — | $14/mo | Costly |
Unattributable Unattributable | Other | 414ms | 0 KB | — | $5/mo | Costly |
Google Tag Manager www.googletagmanager.com | Tag Manager | 397ms | 174 KB | 33% | $5/mo | Costly |
Google Tag Manager www.googletagmanager.com | Tag Manager | 273ms | 173 KB | 42% | $4/mo | Costly |
Google Tag Manager www.googletagmanager.com | Tag Manager | 241ms | 152 KB | 42% | $3/mo | Costly |
Google Tag Manager www.googletagmanager.com | Tag Manager | 234ms | 173 KB | 42% | $3/mo | Costly |
www.brown.edu www.brown.edu | Other | 60ms | 168 KB | — | $1/mo | Optional |
These scripts may cost more than they're worth
- www.brown.edu adds 1700ms and costs ~$23/month
- www.brown.edu adds 1017ms and costs ~$14/month
- Unattributable adds 414ms and costs ~$5/month
- Google Tag Manager adds 397ms and costs ~$5/month
- Google Tag Manager adds 273ms and costs ~$4/month
- Google Tag Manager adds 241ms and costs ~$3/month
- Google Tag Manager adds 234ms 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.brown.edu takes 1700ms 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
53% of www.brown.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
www.brown.edu takes 1017ms 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 414ms 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 397ms 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 273ms 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 241ms 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 234ms 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