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.
640 ms
Largest Contentful Paint Largest Contentful Paint — how long until the largest visible element loads. Under 2.5s is good.
832 ms
Total Blocking Time Total Blocking Time — total time the main thread was blocked, preventing user input. Under 200ms is good.
0 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.
2.31 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.
834 ms
Page Load Progression
FPage Weight BudgetAction2.9 MB transferred, 58 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
CImage OptimizationAction26 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
CPage Weight InventoryAction58 resources · 2.9 MB · 35 KB savings availableREVIEW
~35.4 KiB of savings available
| # | Resource | Type | Size | Cache | Unused | 3rd party | Issues |
|---|---|---|---|---|---|---|---|
| — | — | ||||||
| 58 resources | 2.9 MiB | ||||||
CGreen HostingActionWhether the site is served from green-energy infrastructureREVIEW
Green Hosting
No green hosting detected
A+Third-Party ImpactNo third-party resourcesPASS
A+Text CompressionAll text resources are compressedPASS
A+JS Execution Cost269ms total JS executionPASS
Main Thread Breakdown
| Script | Total | Scripting | Parse/Compile | Party |
|---|---|---|---|---|
| https://ustc.edu.cn/ | 103ms | 3ms | 1ms | 1st |
| Unattributable | 99ms | 2ms | 0ms | 3rd |
| https://ustc.edu.cn/news/js/jquery.js | 66ms | 35ms | 8ms | 1st |
A+Font Loading1 fonts (3 KB)PASS
Web fonts
1
3 KB total
Render-blocking
0
of 1
Dominant font-display
swap
Most common across fonts
Font loading timeline
- 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 ~1 KB and ~2 ms
AJS Bundles17 scripts, 35 KB unusedPASS
Downloaded but never executed on this page.
| Script | Size | Unused | Minified | Party |
|---|---|---|---|---|
| https://ustc.edu.cn/news/js/jquery.js | 84 KB | 35 KB (42%) | ✗ | 1st |
| https://ustc.edu.cn/news/js/jquery.sudy.wp.visitcount.js | 2 KB | — | ✓ | 1st |
| https://ustc.edu.cn/news/js/jquery.sudynav.js | 2 KB | — | ✓ | 1st |
| https://ustc.edu.cn/news/js/modernizr.js | 4 KB | — | ✓ | 1st |
| https://ustc.edu.cn/_sitegray/_sitegray.js | 0 KB | — | ✓ | 1st |
| https://ustc.edu.cn/system/resource/js/vsbscreen.min.js | 1 KB | — | ✓ | 1st |
| https://ustc.edu.cn/system/resource/js/counter.js | 1 KB | — | ✓ | 1st |
| https://ustc.edu.cn/news/js/public.js | 1 KB | — | ✓ | 1st |
| https://ustc.edu.cn/news/js/jquery-migrate.min.js | 4 KB | — | ✓ | 1st |
| https://ustc.edu.cn/system/resource/js/dynclicks.js | 1 KB | — | ✓ | 1st |
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
A+Resource CachingAll resources properly cachedPASS
A+Critical Rendering PathNo render-blocking resourcesPASS
A+Resource HintsNo optimization neededPASS
A+HTTP Cachingmax-age=600 (10 minutes)PASS
private, max-age=600
| Directive | Value | Meaning |
|---|---|---|
| private | — | Only browser cache, not CDN/proxy |
| max-age | 600 | Cache for 10 minutes |
Network Waterfall58 requests over 7232msINFO
Third-Party Script CostPer-script blocking time, transfer cost, and cache headersINFO
| Script | Category | Execution | Transfer | Unused | Monthly Cost | Verdict |
|---|---|---|---|---|---|---|
Unattributable Unattributable | Other | 99ms | 0 KB | — | ¥5/mo | Optional |