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.
1.47 s
Largest Contentful Paint Largest Contentful Paint — how long until the largest visible element loads. Under 2.5s is good.
1.80 s
Total Blocking Time Total Blocking Time — total time the main thread was blocked, preventing user input. Under 200ms is good.
2 ms
Cumulative Layout Shift Cumulative Layout Shift — measures visual stability. How much the page layout shifts during loading. Under 0.1 is good.
0.020
Speed Index Speed Index — how quickly content is visually displayed during load. Under 3.4s is good.
1.70 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.
1.97 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 BudgetAction8.4 MB transferred, 106 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
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
DPage Weight InventoryAction106 resources · 8.4 MB · 239 KB savings availableFIX
~239.4 KiB of savings available
| # | Resource | Type | Size | Cache | Unused | 3rd party | Issues |
|---|---|---|---|---|---|---|---|
| — | — | ||||||
| 106 resources | 8.4 MiB | ||||||
FHTTP CachingActionNo cache headersFIX
No Cache-Control header
Adding a Cache-Control header can significantly improve repeat-visit performance.
CImage OptimizationAction51 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
BJS Execution Cost664ms total JS executionREVIEW
Main Thread Breakdown
| Script | Total | Scripting | Parse/Compile | Party |
|---|---|---|---|---|
| https://www.ipcc.ch/ | 296ms | 1ms | 0ms | 3rd |
| Unattributable | 162ms | 19ms | 0ms | 3rd |
| https://www.ipcc.ch/site/wp-includes/js/jquery/jquery.js?ver=1.12.4-wp | 124ms | 71ms | 2ms | 3rd |
| https://www.ipcc.ch/site/assets/themes/ipcc/resources/bower_components/amcharts3/amcharts/amcharts.js | 82ms | 25ms | 9ms | 3rd |
CJS BundlesAction31 scripts, 239 KB unusedREVIEW
Downloaded but never executed on this page.
| Script | Size | Unused | Minified | Party |
|---|---|---|---|---|
| https://www.googletagmanager.com/gtag/js?id=G-97J7HJ28MR&cx=c>m=4e64k0h2 | 159 KB | 65 KB (41%) | ✓ | 3rd |
| https://www.googletagmanager.com/gtag/js?id=UA-168918890-1 | 125 KB | 64 KB (51%) | ✓ | 3rd |
| https://www.ipcc.ch/site/assets/themes/ipcc/resources/bower_components/amcharts3/amcharts/amcharts.js | 64 KB | 57 KB (89%) | ✓ | 3rd |
| https://connect.facebook.net/en_US/bundle/sdk.js/ | 78 KB | 54 KB (69%) | ✓ | 3rd |
| https://www.ipcc.ch/site/assets/themes/ipcc/resources/bower_components/isotope-packery/packery-mode.pkgd.min.js | 5 KB | — | ✓ | 3rd |
| https://www.ipcc.ch/site/assets/themes/ipcc/resources/bower_components/sticky-kit/jquery.sticky-kit.min.js | 2 KB | — | ✓ | 3rd |
| https://www.ipcc.ch/site/assets/themes/ipcc/resources/bower_components/pe-nav-overlay/nav-overlay.js | 1 KB | — | ✓ | 3rd |
| https://www.ipcc.ch/site/assets/themes/ipcc/resources/bower_components/pe-social-widget/follow-widget.js | 2 KB | — | ✓ | 3rd |
| https://www.ipcc.ch/site/assets/themes/ipcc/resources/bower_components/pe-social-widget/share-widget.js | 2 KB | — | ✓ | 3rd |
| https://www.ipcc.ch/site/assets/themes/ipcc/resources/bower_components/pe-borderize/borderize.js | 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
A+Text CompressionAll text resources are compressedPASS
A+Font Loading6 fonts (146 KB)PASS
Web fonts
6
146 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
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
A+Resource CachingAll resources properly cachedPASS
A+Critical Rendering PathNo render-blocking resourcesPASS
A+Resource HintsNo optimization neededPASS
A+Green HostingWhether the site is served from green-energy infrastructurePASS
Green Hosting
This site is hosted on green energy infrastructure
Provider: Cloudflare
Network Waterfall106 requests over 1694msINFO
Third-Party Script CostPer-script blocking time, transfer cost, and cache headersINFO
| Script | Category | Execution | Transfer | Unused | Monthly Cost | Verdict |
|---|---|---|---|---|---|---|
www.ipcc.ch www.ipcc.ch | Other | 296ms | 12 KB | — | CHF5/mo | Costly |
Unattributable Unattributable | Other | 162ms | 0 KB | — | CHF3/mo | Optional |
www.ipcc.ch www.ipcc.ch | Other | 124ms | 34 KB | — | CHF2/mo | Optional |
www.ipcc.ch www.ipcc.ch | Other | 82ms | 64 KB | 89% | CHF1/mo | Optional |
These scripts may cost more than they're worth
- www.ipcc.ch adds 296ms and costs ~CHF5/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.ipcc.ch takes 296ms 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
89% of www.ipcc.ch'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