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.
1.02 s
Largest Contentful Paint Largest Contentful Paint — how long until the largest visible element loads. Under 2.5s is good.
1.37 s
Total Blocking Time Total Blocking Time — total time the main thread was blocked, preventing user input. Under 200ms is good.
75 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.
1.89 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.
3.57 s
Page Load Progression
FPage Weight BudgetAction3.0 MB transferred, 86 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 BundlesAction33 scripts, 943 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=08aaef225b13ec92c7f2ef87d942173b3a398d68b1f9899c3ec71e25a8bc662d_20260421 | 170 KB | 65 KB (38%) | ✓ | 3rd |
| https://www.googletagmanager.com/gtag/destination?id=DC-14091224&cx=c>m=4e64h1&sign=08aaef225b13ec92c7f2ef87d942173b3a398d68b1f9899c3ec71e25a8bc662d_20260421 | 130 KB | 65 KB (50%) | ✓ | 3rd |
| https://sst.one.com/gtag/js?id=AW-1014528261&cx=c>m=4e64h1&sign=08aaef225b13ec92c7f2ef87d942173b3a398d68b1f9899c3ec71e25a8bc662d_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 | 22 KB (35%) | ✓ | 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 InventoryAction86 resources · 3.0 MB · 943 KB savings availableFIX
~943.5 KiB of savings available
| # | Resource | Type | Size | Cache | Unused | 3rd party | Issues |
|---|---|---|---|---|---|---|---|
| — | — | ||||||
| 86 resources | 3.0 MiB | ||||||
FHTTP CachingActionNo cache headersFIX
No Cache-Control header
Adding a Cache-Control header can significantly improve repeat-visit performance.
BImage Optimization13 images, 0 KB saveableREVIEW
CJS Execution CostAction1734ms total JS executionREVIEW
Main Thread Breakdown
| Script | Total | Scripting | Parse/Compile | Party |
|---|---|---|---|---|
| https://storefront.group-cdn.one/_next/static/chunks/045c83caa4d15373.js | 384ms | 289ms | 5ms | 3rd |
| https://www.one.com/en-gb/ | 342ms | 10ms | 34ms | 3rd |
| https://storefront.group-cdn.one/_next/static/chunks/ee40b2a910b574e0.js | 289ms | 44ms | 7ms | 3rd |
| https://www.gstatic.com/recaptcha/releases/gTpTIWhbKpxADzTzkcabhXN4/recaptcha__en.js | 182ms | 158ms | 19ms | 3rd |
| Unattributable | 176ms | 6ms | 0ms | 3rd |
| https://sst.one.com/gtm.js?id=GTM-KQ4H | 145ms | 126ms | 16ms | 3rd |
| https://consent.cookiebot.eu/b2283f59-b942-44c0-ae40-584bef05ec31/cc.js?renew=false&referer=www.one.com&dnt=false&init=false&culture=en | 85ms | 31ms | 11ms | 3rd |
| https://sst.one.com/gtag/js?id=G-BD66HNTQLT&cx=c>m=4e64h1&sign=08aaef225b13ec92c7f2ef87d942173b3a398d68b1f9899c3ec71e25a8bc662d_20260421 | 75ms | 54ms | 9ms | 3rd |
| https://sst.one.com/gtag/js?id=AW-1014528261&cx=c>m=4e64h1&sign=08aaef225b13ec92c7f2ef87d942173b3a398d68b1f9899c3ec71e25a8bc662d_20260421 | 55ms | 45ms | 10ms | 3rd |
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 HintsNo optimization neededPASS
Network Waterfall86 requests over 3189msINFO
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 | 384ms | 62 KB | 35% | £2/mo | Costly |
www.one.com www.one.com | Other | 342ms | 199 KB | — | £2/mo | Costly |
storefront.group-cdn.one storefront.group-cdn.one | Other | 289ms | 43 KB | — | £2/mo | Costly |
www.gstatic.com www.gstatic.com | Other | 182ms | 0 KB | 49% | £1/mo | Optional |
Unattributable Unattributable | Other | 176ms | 0 KB | — | £1/mo | Optional |
sst.one.com sst.one.com | Other | 145ms | 200 KB | 31% | £1/mo | Optional |
consent.cookiebot.eu consent.cookiebot.eu | Other | 85ms | 80 KB | 36% | £0/mo | Optional |
sst.one.com sst.one.com | Other | 75ms | 170 KB | 38% | £0/mo | Optional |
sst.one.com sst.one.com | Other | 55ms | 145 KB | 43% | £0/mo | Optional |
These scripts may cost more than they're worth
- storefront.group-cdn.one adds 384ms and costs ~£2/month
- www.one.com adds 342ms and costs ~£2/month
- storefront.group-cdn.one adds 289ms and costs ~£2/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 384ms 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 342ms 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 289ms 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