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.
3.65 s
Largest Contentful Paint Largest Contentful Paint — how long until the largest visible element loads. Under 2.5s is good.
6.01 s
Total Blocking Time Total Blocking Time — total time the main thread was blocked, preventing user input. Under 200ms is good.
1.62 s
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.
6.62 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.
21.47 s
Page Load Progression
FPage Weight BudgetAction2.9 MB transferred, 83 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 CostAction9099ms total JS executionFIX
Main Thread Breakdown
| Script | Total | Scripting | Parse/Compile | Party |
|---|---|---|---|---|
| https://storefront.group-cdn.one/_next/static/chunks/045c83caa4d15373.js | 4627ms | 3751ms | 17ms | 3rd |
| https://www.one.com/en-gb/ | 772ms | 31ms | 105ms | 3rd |
| https://www.gstatic.com/recaptcha/releases/gTpTIWhbKpxADzTzkcabhXN4/recaptcha__en.js | 715ms | 607ms | 88ms | 3rd |
| Unattributable | 590ms | 23ms | 0ms | 3rd |
| https://storefront.group-cdn.one/_next/static/chunks/ee40b2a910b574e0.js | 564ms | 91ms | 20ms | 3rd |
| https://sst.one.com/gtm.js?id=GTM-KQ4H | 549ms | 413ms | 66ms | 3rd |
| https://consent.cookiebot.eu/uc.js?cbid=b2283f59-b942-44c0-ae40-584bef05ec31&implementation=gtm&consentmode-dataredaction=dynamic&culture=en | 400ms | 228ms | 14ms | 3rd |
| https://sst.one.com/gtag/js?id=G-BD66HNTQLT&cx=c>m=4e64h1&sign=fc959f8be950988c2eb40d91e32345c41b49f1c3e8d084a35afa83a93e4446fc_20260421 | 292ms | 246ms | 42ms | 3rd |
| https://sst.one.com/gtag/js?id=AW-1014528261&cx=c>m=4e64h1&sign=fc959f8be950988c2eb40d91e32345c41b49f1c3e8d084a35afa83a93e4446fc_20260421 | 247ms | 211ms | 34ms | 3rd |
| https://www.googletagmanager.com/gtag/destination?id=DC-14091224&cx=c>m=4e64h1&sign=fc959f8be950988c2eb40d91e32345c41b49f1c3e8d084a35afa83a93e4446fc_20260421 | 159ms | 124ms | 32ms | 3rd |
Showing top 10 of 12 scripts
FJS BundlesAction33 scripts, 942 KB unusedFIX
Downloaded but never executed on this page.
| Script | Size | Unused | Minified | Party |
|---|---|---|---|---|
| https://www.gstatic.com/recaptcha/releases/gTpTIWhbKpxADzTzkcabhXN4/recaptcha__en.js | 0 KB | 177 KB (49%) | ✓ | 3rd |
| https://www.gstatic.com/recaptcha/releases/gTpTIWhbKpxADzTzkcabhXN4/recaptcha__en.js | 362 KB | 177 KB (49%) | ✓ | 3rd |
| https://www.gstatic.com/recaptcha/releases/gTpTIWhbKpxADzTzkcabhXN4/recaptcha__en.js | 362 KB | 177 KB (49%) | ✓ | 3rd |
| https://js.hsforms.net/forms/v2.js | 194 KB | 108 KB (58%) | ✓ | 3rd |
| https://sst.one.com/gtag/js?id=G-BD66HNTQLT&cx=c>m=4e64h1&sign=fc959f8be950988c2eb40d91e32345c41b49f1c3e8d084a35afa83a93e4446fc_20260421 | 170 KB | 65 KB (38%) | ✓ | 3rd |
| https://www.googletagmanager.com/gtag/destination?id=DC-14091224&cx=c>m=4e64h1&sign=fc959f8be950988c2eb40d91e32345c41b49f1c3e8d084a35afa83a93e4446fc_20260421 | 130 KB | 65 KB (50%) | ✓ | 3rd |
| https://sst.one.com/gtag/js?id=AW-1014528261&cx=c>m=4e64h1&sign=fc959f8be950988c2eb40d91e32345c41b49f1c3e8d084a35afa83a93e4446fc_20260421 | 145 KB | 63 KB (43%) | ✓ | 3rd |
| https://sst.one.com/gtm.js?id=GTM-KQ4H | 200 KB | 62 KB (31%) | ✓ | 3rd |
| https://consent.cookiebot.eu/b2283f59-b942-44c0-ae40-584bef05ec31/cc.js?renew=false&referer=www.one.com&dnt=false&init=false&culture=en | 80 KB | 29 KB (36%) | ✓ | 3rd |
| https://storefront.group-cdn.one/_next/static/chunks/045c83caa4d15373.js | 62 KB | 21 KB (33%) | ✓ | 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 InventoryAction83 resources · 2.9 MB · 942 KB savings availableFIX
~941.6 KiB of savings available
| # | Resource | Type | Size | Cache | Unused | 3rd party | Issues |
|---|---|---|---|---|---|---|---|
| — | — | ||||||
| 83 resources | 2.9 MiB | ||||||
FHTTP CachingActionNo cache headersFIX
No Cache-Control header
Adding a Cache-Control header can significantly improve repeat-visit performance.
BImage Optimization11 images, 0 KB saveableREVIEW
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 Loading3 fonts (145 KB)PASS
Web fonts
3
145 KB total
Render-blocking
0
of 3
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 Hints5 hints, 0 missing preconnectsPASS
Current Resource Hints
5 resource hints configured
A+Render-Blocking ResourcesNo render-blocking resources detectedPASS
A+Third-Party ResourcesNo third-party resources detectedPASS
Network Waterfall83 requests over 3507msINFO
Third-Party Script CostPer-script blocking time, transfer cost, and cache headersINFO
| Script | Category | Execution | Transfer | Unused | Monthly Cost | Verdict |
|---|---|---|---|---|---|---|
storefront.group-cdn.one storefront.group-cdn.one | Other | 4627ms | 62 KB | 33% | £24/mo | Costly |
www.one.com www.one.com | Other | 772ms | 199 KB | — | £4/mo | Costly |
www.gstatic.com www.gstatic.com | Other | 715ms | 0 KB | 49% | £4/mo | Costly |
Unattributable Unattributable | Other | 590ms | 0 KB | — | £3/mo | Costly |
storefront.group-cdn.one storefront.group-cdn.one | Other | 564ms | 43 KB | — | £3/mo | Costly |
sst.one.com sst.one.com | Other | 549ms | 200 KB | 31% | £3/mo | Costly |
consent.cookiebot.eu consent.cookiebot.eu | Other | 400ms | 30 KB | — | £2/mo | Costly |
sst.one.com sst.one.com | Other | 292ms | 170 KB | 38% | £2/mo | Costly |
sst.one.com sst.one.com | Other | 247ms | 145 KB | 43% | £1/mo | Costly |
Google Tag Manager www.googletagmanager.com | Tag Manager | 159ms | 130 KB | 50% | £1/mo | Optional |
js.hsforms.net js.hsforms.net | Other | 112ms | 194 KB | 58% | £1/mo | Optional |
js.hsforms.net js.hsforms.net | Other | 72ms | 15 KB | — | £0/mo | Optional |
These scripts may cost more than they're worth
- storefront.group-cdn.one adds 4627ms and costs ~£24/month
- www.one.com adds 772ms and costs ~£4/month
- www.gstatic.com adds 715ms and costs ~£4/month
- Unattributable adds 590ms and costs ~£3/month
- storefront.group-cdn.one adds 564ms and costs ~£3/month
- sst.one.com adds 549ms and costs ~£3/month
- consent.cookiebot.eu adds 400ms and costs ~£2/month
- sst.one.com adds 292ms and costs ~£2/month
- sst.one.com adds 247ms and costs ~£1/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
storefront.group-cdn.one takes 4627ms 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.one.com takes 772ms 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.gstatic.com takes 715ms 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 590ms 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
storefront.group-cdn.one takes 564ms 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
sst.one.com takes 549ms 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
consent.cookiebot.eu takes 400ms 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
sst.one.com takes 292ms 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
sst.one.com takes 247ms 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
50% of Google Tag Manager'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
58% of js.hsforms.net'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