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.
2.33 s
Largest Contentful Paint Largest Contentful Paint — how long until the largest visible element loads. Under 2.5s is good.
6.36 s
Total Blocking Time Total Blocking Time — total time the main thread was blocked, preventing user input. Under 200ms is good.
777 ms
Cumulative Layout Shift Cumulative Layout Shift — measures visual stability. How much the page layout shifts during loading. Under 0.1 is good.
0.057
Speed Index Speed Index — how quickly content is visually displayed during load. Under 3.4s is good.
3.82 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.
8.93 s
Page Load Progression
DPage Weight BudgetAction2.1 MB transferred, 99 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
DThird-Party ImpactAction100% third-party, 0 ms blockingFIX
FJS Execution CostAction3699ms total JS executionFIX
Main Thread Breakdown
| Script | Total | Scripting | Parse/Compile | Party |
|---|---|---|---|---|
| https://www.penguin.co.uk/_next/static/chunks/framework-945b357d4a851f4b.js | 1030ms | 923ms | 12ms | 3rd |
| https://www.penguin.co.uk/ | 1021ms | 21ms | 2ms | 3rd |
| Unattributable | 674ms | 119ms | 0ms | 3rd |
| https://cdn-ukwest.onetrust.com/scripttemplates/202602.1.0/otBannerSdk.js | 344ms | 210ms | 39ms | 3rd |
| https://www.penguin.co.uk/_next/static/chunks/pages/_app-7349391626bb9263.js | 170ms | 137ms | 32ms | 3rd |
| https://www.penguin.co.uk/newrelicmonitoring.min.js | 151ms | 81ms | 3ms | 3rd |
| https://www.penguin.co.uk/_next/static/chunks/pages/index-6e6ac7810b55ebd6.js | 132ms | 131ms | 0ms | 3rd |
| https://www.penguin.co.uk/_next/static/chunks/main-fd62e7a6acd89978.js | 91ms | 79ms | 8ms | 3rd |
| https://www.penguin.co.uk/_next/static/chunks/1073-d6fd4d7618df984c.js | 86ms | 4ms | 12ms | 3rd |
DPage Weight InventoryAction99 resources · 2.1 MB · 237 KB savings availableFIX
~237.4 KiB of savings available
| # | Resource | Type | Size | Cache | Unused | 3rd party | Issues |
|---|---|---|---|---|---|---|---|
| — | — | ||||||
| 99 resources | 2.1 MiB | ||||||
FHTTP CachingActionNo cache headersFIX
No Cache-Control header
Adding a Cache-Control header can significantly improve repeat-visit performance.
BImage Optimization24 images, 0 KB saveableREVIEW
CJS BundlesAction35 scripts, 237 KB unusedREVIEW
Downloaded but never executed on this page.
| Script | Size | Unused | Minified | Party |
|---|---|---|---|---|
| https://cdn-ukwest.onetrust.com/scripttemplates/202602.1.0/otBannerSdk.js | 129 KB | 68 KB (52%) | ✓ | 3rd |
| https://www.penguin.co.uk/_next/static/chunks/pages/_app-7349391626bb9263.js | 119 KB | 49 KB (41%) | ✓ | 3rd |
| https://www.penguin.co.uk/_next/static/chunks/2164-7f327a12c62636eb.js | 0 KB | 41 KB (69%) | ✓ | 3rd |
| https://www.penguin.co.uk/_next/static/chunks/2164-7f327a12c62636eb.js | 20 KB | 41 KB (69%) | ✓ | 3rd |
| https://www.penguin.co.uk/_next/static/chunks/5223-5f7a5e00a03bf759.js | 68 KB | 40 KB (58%) | ✓ | 3rd |
| https://www.penguin.co.uk/_next/static/chunks/1073-d6fd4d7618df984c.js | 33 KB | — | ✓ | 3rd |
| https://js-agent.newrelic.com/nr-spa-1216.min.js | 17 KB | — | ✓ | 3rd |
| https://www.penguin.co.uk/_next/static/chunks/framework-945b357d4a851f4b.js | 44 KB | — | ✓ | 3rd |
| https://www.everestjs.net/static/le/last-event-tag-latest.min.js | 0 KB | — | ✓ | 3rd |
| https://www.penguin.co.uk/_next/static/chunks/3577-eb0c1b303aa813bc.js | 8 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
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 Loading9 fonts (190 KB)PASS
Web fonts
9
190 KB total
Render-blocking
0
of 9
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 Hints18 hints, 0 missing preconnectsPASS
Current Resource Hints
18 resource hints configured
A+Render-Blocking ResourcesNo render-blocking resources detectedPASS
A+Third-Party ResourcesNo third-party resources detectedPASS
Network Waterfall99 requests over 1573msINFO
Third-Party Script CostPer-script blocking time, transfer cost, and cache headersINFO
| Script | Category | Execution | Transfer | Unused | Monthly Cost | Verdict |
|---|---|---|---|---|---|---|
www.penguin.co.uk www.penguin.co.uk | Other | 1030ms | 44 KB | — | £11/mo | Costly |
www.penguin.co.uk www.penguin.co.uk | Other | 1021ms | 68 KB | — | £11/mo | Costly |
Unattributable Unattributable | Other | 674ms | 0 KB | — | £7/mo | Costly |
cdn-ukwest.onetrust.com cdn-ukwest.onetrust.com | Other | 344ms | 129 KB | 52% | £4/mo | Costly |
www.penguin.co.uk www.penguin.co.uk | Other | 170ms | 119 KB | 41% | £2/mo | Optional |
www.penguin.co.uk www.penguin.co.uk | Other | 151ms | 12 KB | — | £2/mo | Optional |
www.penguin.co.uk www.penguin.co.uk | Other | 132ms | 1 KB | — | £1/mo | Optional |
www.penguin.co.uk www.penguin.co.uk | Other | 91ms | 38 KB | — | £1/mo | Optional |
www.penguin.co.uk www.penguin.co.uk | Other | 86ms | 33 KB | — | £1/mo | Optional |
These scripts may cost more than they're worth
- www.penguin.co.uk adds 1030ms and costs ~£11/month
- www.penguin.co.uk adds 1021ms and costs ~£11/month
- Unattributable adds 674ms and costs ~£7/month
- cdn-ukwest.onetrust.com adds 344ms 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.penguin.co.uk takes 1030ms 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.penguin.co.uk takes 1021ms 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 674ms 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
cdn-ukwest.onetrust.com takes 344ms 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
52% of cdn-ukwest.onetrust.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