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.
8.21 s
Largest Contentful Paint Largest Contentful Paint — how long until the largest visible element loads. Under 2.5s is good.
18.43 s
Total Blocking Time Total Blocking Time — total time the main thread was blocked, preventing user input. Under 200ms is good.
6.37 s
Cumulative Layout Shift Cumulative Layout Shift — measures visual stability. How much the page layout shifts during loading. Under 0.1 is good.
0.030
Speed Index Speed Index — how quickly content is visually displayed during load. Under 3.4s is good.
11.37 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.
18.66 s
Page Load Progression
FPage Weight BudgetAction3.9 MB transferred, 183 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
FJS Execution CostAction10029ms total JS executionFIX
Main Thread Breakdown
| Script | Total | Scripting | Parse/Compile | Party |
|---|---|---|---|---|
| https://www.oclc.org/etc.clientlibs/oclc/clientlibs/oclc/jquery.min.js | 5644ms | 5577ms | 10ms | 3rd |
| https://www.oclc.org/en/home.html?redirect=true | 1637ms | 842ms | 100ms | 3rd |
| Unattributable | 945ms | 167ms | 0ms | 3rd |
| https://www.googletagmanager.com/gtm.js?id=GTM-TC83QFB | 478ms | 399ms | 68ms | 3rd |
| https://static.cloud.coveo.com/atomic/v3/6610-0d18ce17.js | 281ms | 227ms | 0ms | 3rd |
| https://cdn.cookielaw.org/scripttemplates/202505.1.0/otBannerSdk.js | 216ms | 129ms | 35ms | 3rd |
| https://www.oclc.org/apps/oclc/clientlibs/oclc/jquery-ui/source/jquery-ui.min.js | 185ms | 52ms | 131ms | 3rd |
| https://www.oclc.org/etc.clientlibs/clientlibs/social/thirdparty/ckeditor.min.js | 150ms | 59ms | 86ms | 3rd |
| https://www.oclc.org/apps/settings/wcm/designs/oclc/js/mainnavigation-functions-v0.3.js | 93ms | 66ms | 2ms | 3rd |
| https://static.cloud.coveo.com/atomic/v3/6577-1eb70d3c.js | 77ms | 75ms | 0ms | 3rd |
Showing top 10 of 15 scripts
FJS BundlesAction119 scripts, 979 KB unusedFIX
Downloaded but never executed on this page.
| Script | Size | Unused | Minified | Party |
|---|---|---|---|---|
| https://www.oclc.org/etc.clientlibs/clientlibs/social/thirdparty/ckeditor.min.js | 232 KB | 202 KB (87%) | ✓ | 3rd |
| https://static.cloud.coveo.com/headless/v3.49.3/headless.esm.js | 170 KB | 123 KB (73%) | ✓ | 3rd |
| https://www.oclc.org/apps/oclc/clientlibs/oclc/jquery-ui/source/jquery-ui.min.js | 0 KB | 113 KB (86%) | ✗ | 3rd |
| https://www.oclc.org/apps/oclc/clientlibs/oclc/jquery-ui/source/jquery-ui.min.js | 695 KB | 113 KB (86%) | ✗ | 3rd |
| https://www.oclc.org/apps/oclc/clientlibs/oclc/jquery-ui/source/jquery-ui.min.js | 132 KB | 113 KB (86%) | ✗ | 3rd |
| https://www.googletagmanager.com/gtm.js?id=GTM-TC83QFB | 188 KB | 85 KB (45%) | ✓ | 3rd |
| https://cdn.cookielaw.org/scripttemplates/202505.1.0/otBannerSdk.js | 119 KB | 75 KB (63%) | ✓ | 3rd |
| https://www.oclc.org/etc.clientlibs/clientlibs/granite/jquery-ui.min.js | 70 KB | 60 KB (87%) | ✓ | 3rd |
| https://www.oclc.org/apps/oclc/clientlibs/oclc/jquery-ui.min.js | 68 KB | 59 KB (87%) | ✓ | 3rd |
| https://static.cloud.coveo.com/atomic/v3/npm.dayjs-2661949a.js | 42 KB | 36 KB (99%) | ✓ | 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 InventoryAction183 resources · 3.9 MB · 979 KB savings availableFIX
~979.0 KiB of savings available
| # | Resource | Type | Size | Cache | Unused | 3rd party | Issues |
|---|---|---|---|---|---|---|---|
| — | — | ||||||
| 183 resources | 3.9 MiB | ||||||
FHTTP CachingActionNo cache headersFIX
No Cache-Control header
Adding a Cache-Control header can significantly improve repeat-visit performance.
CImage OptimizationAction27 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
A+Text CompressionAll text resources are compressedPASS
A+Font Loading5 fonts (164 KB)PASS
Web fonts
5
164 KB total
Render-blocking
0
of 5
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 Hints1 hints, 0 missing preconnectsPASS
Current Resource Hints
1 resource hints configured
A+Render-Blocking ResourcesNo render-blocking resources detectedPASS
A+Third-Party ResourcesNo third-party resources detectedPASS
A+Green HostingWhether the site is served from green-energy infrastructurePASS
Green Hosting
This site is hosted on green energy infrastructure
Provider: Cloudflare
Network Waterfall183 requests over 11082msINFO
Third-Party Script CostPer-script blocking time, transfer cost, and cache headersINFO
| Script | Category | Execution | Transfer | Unused | Monthly Cost | Verdict |
|---|---|---|---|---|---|---|
www.oclc.org www.oclc.org | Other | 5644ms | 32 KB | — | €90/mo | Costly |
www.oclc.org www.oclc.org | Other | 1637ms | 15 KB | — | €26/mo | Costly |
Unattributable Unattributable | Other | 945ms | 0 KB | — | €15/mo | Costly |
Google Tag Manager www.googletagmanager.com | Tag Manager | 478ms | 188 KB | 45% | €8/mo | Costly |
static.cloud.coveo.com static.cloud.coveo.com | Other | 281ms | 10 KB | — | €4/mo | Costly |
OneTrust cdn.cookielaw.org | Consent | 216ms | 119 KB | 63% | €3/mo | Essential |
www.oclc.org www.oclc.org | Other | 185ms | 0 KB | 86% | €3/mo | Optional |
www.oclc.org www.oclc.org | Other | 150ms | 232 KB | 87% | €2/mo | Optional |
www.oclc.org www.oclc.org | Other | 93ms | 0 KB | — | €1/mo | Optional |
static.cloud.coveo.com static.cloud.coveo.com | Other | 77ms | 2 KB | — | €1/mo | Optional |
www.oclc.org www.oclc.org | Other | 77ms | 2 KB | — | €1/mo | Optional |
www.oclc.org www.oclc.org | Other | 73ms | 6 KB | — | €1/mo | Optional |
www.oclc.org www.oclc.org | Other | 63ms | 68 KB | 87% | €1/mo | Optional |
dev.visualwebsiteoptimizer.com dev.visualwebsiteoptimizer.com | Other | 57ms | 27 KB | — | €1/mo | Optional |
www.oclc.org www.oclc.org | Other | 54ms | 70 KB | 87% | €1/mo | Optional |
These scripts may cost more than they're worth
- www.oclc.org adds 5644ms and costs ~€90/month
- www.oclc.org adds 1637ms and costs ~€26/month
- Unattributable adds 945ms and costs ~€15/month
- Google Tag Manager adds 478ms and costs ~€8/month
- static.cloud.coveo.com adds 281ms 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.oclc.org takes 5644ms 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
www.oclc.org takes 1637ms 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 945ms 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 478ms 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
static.cloud.coveo.com takes 281ms 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
63% of OneTrust'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
86% of www.oclc.org'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
87% of www.oclc.org'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
87% of www.oclc.org'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
87% of www.oclc.org'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