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.
720 ms
Largest Contentful Paint Largest Contentful Paint — how long until the largest visible element loads. Under 2.5s is good.
1.48 s
Total Blocking Time Total Blocking Time — total time the main thread was blocked, preventing user input. Under 200ms is good.
61 ms
Cumulative Layout Shift Cumulative Layout Shift — measures visual stability. How much the page layout shifts during loading. Under 0.1 is good.
0.054
Speed Index Speed Index — how quickly content is visually displayed during load. Under 3.4s is good.
1.11 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.
5.69 s
Page Load Progression
375 ms
750 ms 1.1 s 1.5 s 1.9 s 2.2 s 2.6 s 3.0 sFPage Weight BudgetAction4.0 MB transferred, 107 requestsFIX
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
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
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 BundlesAction32 scripts, 632 KB unusedFIX
Downloaded but never executed on this page.
| Script | Size | Unused | Minified | Party |
|---|---|---|---|---|
| https://translate.googleapis.com/_/translate_http/_/js/k=translate_http.tr.es.tx2xLY0E1vs.O/am=AAAAAQ/d=1/exm=el_conf/ed=1/rs=AN8SPfqpxCvJC7xM-EE7YNgj9y6xTg0LGA/m=el_main | 118 KB | 93 KB (79%) | ✓ | 3rd |
| https://www.googletagmanager.com/gtm.js?id=GTM-M3DX2QP | 193 KB | 73 KB (38%) | ✓ | 3rd |
| https://www.googletagmanager.com/gtag/js?id=AW-958535370&cx=c>m=4e64h1h1 | 145 KB | 65 KB (45%) | ✓ | 3rd |
| https://www.googletagmanager.com/gtag/js?id=G-WW2LE17NC1&cx=c>m=4e64h1h1 | 169 KB | 64 KB (38%) | ✓ | 3rd |
| https://analytics.tiktok.com/i18n/pixel/static/main.MWE0ZWQ3ZWQwOA.js | 117 KB | 63 KB (54%) | ✓ | 3rd |
| https://www.googletagmanager.com/gtag/destination?id=AW-10798108385&cx=c>m=4e64h1h1 | 138 KB | 61 KB (44%) | ✓ | 3rd |
| https://www.googletagmanager.com/gtag/destination?id=DC-12399946&cx=c>m=4e64h1h1 | 131 KB | 59 KB (45%) | ✓ | 3rd |
| https://www.googletagmanager.com/gtag/destination?id=DC-12320119&cx=c>m=4e64h1h1 | 131 KB | 57 KB (44%) | ✓ | 3rd |
| https://www.colorado.edu/sites/default/files/js/js_UAM_9otwUAyHzZOeb4woD4suuEdijCa5oFxi2zBWJx4.js?scope=footer&delta=1&language=en&theme=boulder_base&include=eJx1jUEOwjAMBD9E6I07F74R2a0VQp24ih1Bf09pAIkCF0s7O1qjVB6oeASlrvboAgsC73DLEwVYTq4OWfrxl5DrN1WC0p8dyu1vl2RYHgaRwOQNQheWs817uMDtE6bdMuJRxNQKTJ5hlmq6Tr-pe9LV7SFNVX2ma7Nado_c-pGGaFL8xDXErN0LuAac2szUXDvHMvgJis2eIxYokbQ7SbbjlVQSHe5tUIZt | 54 KB | 39 KB (73%) | ✓ | 3rd |
| https://connect.facebook.net/en_US/fbevents.js | 97 KB | 33 KB (34%) | ✓ | 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 InventoryAction107 resources · 4.0 MB · 632 KB savings availableFIX
~632.4 KiB of savings available
| # | Resource | Type | Size | Cache | Unused | 3rd party | Issues |
|---|---|---|---|---|---|---|---|
| — | — | ||||||
| 107 resources | 4.0 MiB | ||||||
FHTTP CachingActionNo cache headersFIX
No Cache-Control header
Adding a Cache-Control header can significantly improve repeat-visit performance.
CImage OptimizationAction31 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 CostAction1116ms total JS executionREVIEW
Main Thread Breakdown
| Script | Total | Scripting | Parse/Compile | Party |
|---|---|---|---|---|
| https://www.colorado.edu/ | 360ms | 2ms | 0ms | 3rd |
| Unattributable | 150ms | 10ms | 0ms | 3rd |
| https://www.googletagmanager.com/gtm.js?id=GTM-M3DX2QP | 143ms | 117ms | 19ms | 3rd |
| https://www.colorado.edu/modules/custom/ucb_third_party_libraries/js/FontAwesome/all.min.js?v=1 | 90ms | 36ms | 34ms | 3rd |
| https://www.googletagmanager.com/gtag/js?id=G-WW2LE17NC1&cx=c>m=4e64h1h1 | 84ms | 63ms | 20ms | 3rd |
| https://analytics.tiktok.com/i18n/pixel/static/main.MWE0ZWQ3ZWQwOA.js | 72ms | 61ms | 11ms | 3rd |
| https://www.googletagmanager.com/gtag/destination?id=DC-12399946&cx=c>m=4e64h1h1 | 56ms | 47ms | 9ms | 3rd |
| https://translate.googleapis.com/_/translate_http/_/js/k=translate_http.tr.es.tx2xLY0E1vs.O/am=AAAAAQ/d=1/exm=el_conf/ed=1/rs=AN8SPfqpxCvJC7xM-EE7YNgj9y6xTg0LGA/m=el_main | 55ms | 40ms | 12ms | 3rd |
| https://www.googletagmanager.com/gtag/destination?id=AW-10798108385&cx=c>m=4e64h1h1 | 54ms | 43ms | 11ms | 3rd |
| https://www.googletagmanager.com/gtag/js?id=AW-958535370&cx=c>m=4e64h1h1 | 51ms | 43ms | 8ms | 3rd |
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 Loading1 fonts (37 KB)PASS
Web fonts
1
37 KB total
Render-blocking
0
of 1
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 Waterfall107 requests over 1827msINFO
Third-Party Script CostPer-script blocking time, transfer cost, and cache headersINFO
| Script | Category | Execution | Transfer | Unused | Monthly Cost | Verdict |
|---|---|---|---|---|---|---|
www.colorado.edu www.colorado.edu | Other | 360ms | 18 KB | — | €4/mo | Costly |
Unattributable Unattributable | Other | 150ms | 0 KB | — | €2/mo | Optional |
Google Tag Manager www.googletagmanager.com | Tag Manager | 143ms | 193 KB | 38% | €2/mo | Optional |
www.colorado.edu www.colorado.edu | Other | 90ms | 633 KB | — | €1/mo | Optional |
Google Tag Manager www.googletagmanager.com | Tag Manager | 84ms | 169 KB | 38% | €1/mo | Optional |
analytics.tiktok.com analytics.tiktok.com | Other | 72ms | 117 KB | 54% | €1/mo | Optional |
Google Tag Manager www.googletagmanager.com | Tag Manager | 56ms | 131 KB | 45% | €1/mo | Optional |
translate.googleapis.com translate.googleapis.com | Other | 55ms | 118 KB | 79% | €1/mo | Optional |
Google Tag Manager www.googletagmanager.com | Tag Manager | 54ms | 138 KB | 44% | €1/mo | Optional |
Google Tag Manager www.googletagmanager.com | Tag Manager | 51ms | 145 KB | 45% | €1/mo | Optional |
These scripts may cost more than they're worth
- www.colorado.edu adds 360ms and costs ~€4/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.colorado.edu takes 360ms 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
54% of analytics.tiktok.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
79% of translate.googleapis.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