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https://www.rightmove.co.uk

Performance

· 14 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
77
GRADE
C
FIX
4
REVIEW
3
PASS
5
INFO
2

Performance-focused optimization plan with CWV assessment, top offenders, and time estimates

Mobile Desktop
91
Performance Overall performance score (0–100) based on Core Web Vitals and other metrics. 90+ is good.
100
Accessibility Measures how accessible the page is for users with disabilities. Checks color contrast, ARIA labels, and semantic HTML.
96
Best Practices Checks for modern web development best practices including HTTPS, no console errors, and secure JavaScript.
100
SEO Measures basic SEO optimizations: meta tags, crawlability, link text, and mobile friendliness.

First Contentful Paint First Contentful Paint — how long until the browser renders the first piece of content. Under 1.8s is good.

630 ms

Largest Contentful Paint Largest Contentful Paint — how long until the largest visible element loads. Under 2.5s is good.

1.56 s

Total Blocking Time Total Blocking Time — total time the main thread was blocked, preventing user input. Under 200ms is good.

145 ms

Cumulative Layout Shift Cumulative Layout Shift — measures visual stability. How much the page layout shifts during loading. Under 0.1 is good.

0.001

Speed Index Speed Index — how quickly content is visually displayed during load. Under 3.4s is good.

883 ms

Time to Interactive Time to Interactive — how long until the page is fully interactive and responds to user input. Under 3.8s is good.

2.47 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 s
Checks
14
5 PASS 3 REVIEW 4 FIX
D
Page Weight Budget
Action
2.5 MB transferred, 46 requests
FIX
2.5 MB transferred, 46 requests
Warning::
Page weighs 7.1 MB (2.5 MB transferred)
Warning::
JavaScript is 1.6 MB — consider code splitting or lazy loading
Large JavaScript bundles delay interactivity. Split code by route or defer non-critical scripts.
Got: 1.6 MB
Info::
46 HTTP requests
Info::
Estimated 0.52 g CO2 per page load
2.5 MB / 2.4 MB budget
2.5 MB transferred
46 requests
0.52 g CO2 per page load
JavaScript 1.6 MiB 65%
Images 730.4 KiB 29%
HTML 54.0 KiB 2%
Fonts 52.4 KiB 2%
CSS 49.6 KiB 2%
Other 4.1 KiB 0%
Other 4.0 KiB 0%
Other 820 B 0%
Other 0 B 0%
0 2.4 MB 4.9 MB
Over budget

Large JavaScript bundles delay interactivity. Split code by route or defer non-critical scripts.

Why this matters

JavaScript bundle is large — code-split routes and lazy-load off-screen components to defer.

Source: web.dev

D
Third-Party Impact
Action
81% third-party, 0 ms blocking
FIX
81% third-party, 0 ms blocking
Warning::
Third-party code accounts for 81% of page weight (2.0 MiB of 2.5 MiB)
Info::
Third-party blocking time is low (0 ms)
19%
81%
First-party Third-party
F
JS Bundles
Action
19 scripts, 777 KB unused
FIX
19 scripts, 777 KB unused
Warning::
https://media.rightmove.co.uk/assets/7fb0c8adf9bad...: 174 KB unused (69%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.rightmove.co.uk/federated/assets/61391...: 101 KB unused (71%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.googletagmanager.com/gtag/js?id=G-Z2N6...: 67 KB unused (40%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.googletagmanager.com/gtag/js?id=AW-792...: 64 KB unused (47%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.googletagmanager.com/gtag/js?id=AW-104...: 64 KB unused (47%)
Consider code splitting or tree shaking to reduce unused code.
Info::
Total unused JavaScript: 777 KB
777 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://media.rightmove.co.uk/assets/7fb0c8adf9bad14b85d82c635308c18c/main.bundle.4c0eb3191280858c4d89.js251 KB174 KB (69%)✓3rd
https://www.rightmove.co.uk/federated/assets/61391f644effa772267c6525fd386cba/client/918-5174d3bb46ddc7cd5d60.js143 KB101 KB (71%)✓1st
https://www.googletagmanager.com/gtag/js?id=G-Z2N66DNEZM&l=rightmoveDataLayer&cx=c&gtm=4e6460h1168 KB67 KB (40%)✓3rd
https://www.googletagmanager.com/gtag/js?id=AW-792861408&l=rightmoveDataLayer&cx=c&gtm=4e6460h1136 KB64 KB (47%)✓3rd
https://www.googletagmanager.com/gtag/js?id=AW-1046760651&l=rightmoveDataLayer&cx=c&gtm=4e6460h1136 KB64 KB (47%)✓3rd
https://www.googletagmanager.com/gtm.js?id=GTM-MVTJNDT&l=rightmoveDataLayer123 KB64 KB (52%)✓3rd
https://www.googletagmanager.com/gtag/js?id=DC-14702053&l=rightmoveDataLayer&cx=c&gtm=4e6460h1129 KB62 KB (48%)✓3rd
https://www.googletagmanager.com/gtag/js?id=DC-9049902&l=rightmoveDataLayer&cx=c&gtm=4e6460h1129 KB59 KB (46%)✓3rd
https://www.googletagmanager.com/gtm.js?id=GTM-5RSKHCJL&l=rightmoveDataLayer&gtm=4e6460h1197 KB57 KB (29%)✓3rd
https://www.googletagmanager.com/gtm.js?id=GTM-PCCWWRS&l=rightmoveDataLayer&gtm=4e6460h1166 KB44 KB (27%)✓3rd

Consider code splitting or tree shaking to reduce unused code.

Why this matters

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.

Why this matters

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.

Why this matters

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.

Why this matters

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.

Why this matters

This bundle has high unused code — code-split or tree-shake to ship only what executes.

Source: web.dev / Lighthouse coverage

F
HTTP Caching
Action
No cache headers
FIX
No cache headers
Warning::
No Cache-Control header found
Browsers will use heuristic caching, which can be unpredictable. Set explicit cache headers.

No Cache-Control header

Adding a Cache-Control header can significantly improve repeat-visit performance.

B
Image Optimization
10 images, 0 KB saveable
REVIEW
10 images, 0 KB saveable
Info::
All images are well-optimized
10 images 730 KB
0 oversized -0 KB
7 legacy format
0 missing dimensions CLS risk
B
JS Execution Cost
829ms total JS execution
REVIEW
829ms total JS execution
Info::
https://www.googletagmanager.com/gtm.js?id=GTM-PCC...: 204ms CPU time
Info::
https://media.rightmove.co.uk/assets/7fb0c8adf9bad...: 128ms CPU time
Info::
https://www.rightmove.co.uk/: 109ms CPU time
Info::
https://www.googletagmanager.com/gtm.js?id=GTM-5RS...: 104ms CPU time
Info::
https://www.googletagmanager.com/gtm.js?id=GTM-MVT...: 95ms CPU time
Warning::
Third-party scripts: 720ms (87% of total)

Main Thread Breakdown

Script Evaluation 66% Script Parsing & Compilation 16% Other 10% Style & Layout 5%
ScriptTotalScriptingParse/CompileParty
https://www.googletagmanager.com/gtm.js?id=GTM-PCCWWRS&l=rightmoveDataLayer&gtm=4e6460h1204ms171ms18ms3rd
https://media.rightmove.co.uk/assets/7fb0c8adf9bad14b85d82c635308c18c/main.bundle.4c0eb3191280858c4d89.js128ms82ms42ms3rd
https://www.rightmove.co.uk/109ms10ms5ms1st
https://www.googletagmanager.com/gtm.js?id=GTM-5RSKHCJL&l=rightmoveDataLayer&gtm=4e6460h1104ms83ms20ms3rd
https://www.googletagmanager.com/gtm.js?id=GTM-MVTJNDT&l=rightmoveDataLayer95ms74ms18ms3rd
Unattributable66ms6ms0ms3rd
https://www.googletagmanager.com/gtag/js?id=G-Z2N66DNEZM&l=rightmoveDataLayer&cx=c&gtm=4e6460h163ms53ms10ms3rd
https://media.rightmove.co.uk/assets/7fb0c8adf9bad14b85d82c635308c18c/shared.bundle.ce72b57457c9cd546ee9.js60ms52ms6ms3rd
C
Green Hosting
Action
Whether the site is served from green-energy infrastructure
REVIEW

Green Hosting

No green hosting detected

A+
Text Compression
All text resources are compressed
PASS
All text resources are compressed
Info::
All text resources are compressed
All text resources are properly compressed.
A+
Font Loading
2 fonts (52 KB)
PASS
2 fonts (52 KB)
Info::
2 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

2

52 KB total

Render-blocking

0

of 2

Dominant font-display

swap

Most common across fonts

Font loading timeline
Transfer FOIT (block) FOUT (swap)
0 ms 500 ms 1.0 s 1.5 s FCP 630 ms LCP 1.6 shttps://media.rightmove.co.uk/assets/shared-fonts/effra/Effra_WLatn_Md.woff2Effra_WLatn_Md.woff2 https://media.rightmove.co.uk/assets/shared-fonts/effra/Effra_WLatn_Md.woff2 — 25.9 KiB — 0 ms — font-display: swaphttps://media.rightmove.co.uk/assets/shared-fonts/effra/Effra_WLatn_Rg.woff2Effra_WLatn_Rg.woff2 https://media.rightmove.co.uk/assets/shared-fonts/effra/Effra_WLatn_Rg.woff2 — 26.5 KiB — 0 ms — font-display: swap
Effra_WLatn_Md.woff2 woff2 swap
Size 26 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
Effra_WLatn_Rg.woff2 woff2 swap
Size 26 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
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 Caching
All resources properly cached
PASS
All resources properly cached
Info::
No caching issues found
All static resources have appropriate caching headers.
A+
Critical Rendering Path
No render-blocking resources
PASS
No render-blocking resources
Info::
No render-blocking resources detected
A+
Resource Hints
No optimization needed
PASS
No optimization needed
Info::
No resource hint issues
Network Waterfall
46 requests over 0ms
INFO

Performance analysis not available for this result.

Third-Party Script Cost
Per-script blocking time, transfer cost, and cache headers
INFO
87% of JavaScript execution is third-party
First-party Third-party 720ms · 967KB · £7/mo
Google Tag Manager
Tag Manager
Costly
Execution 204ms
Transfer 166 KB
Unused 27%
Monthly Cost £2/mo
media.rightmove.co.uk
Other
Optional
Execution 128ms
Transfer 251 KB
Unused 69%
Monthly Cost £1/mo
Google Tag Manager
Tag Manager
Optional
Execution 104ms
Transfer 197 KB
Unused 29%
Monthly Cost £1/mo
Google Tag Manager
Tag Manager
Optional
Execution 95ms
Transfer 123 KB
Unused 52%
Monthly Cost £1/mo
Unattributable
Other
Optional
Execution 66ms
Transfer 0 KB
Monthly Cost £1/mo
Google Tag Manager
Tag Manager
Optional
Execution 63ms
Transfer 168 KB
Unused 40%
Monthly Cost £1/mo
media.rightmove.co.uk
Other
Optional
Execution 60ms
Transfer 63 KB
Unused 35%
Monthly Cost £1/mo

These scripts may cost more than they're worth

  • Google Tag Manager adds 204ms and costs ~£2/month

87% of JavaScript execution time is spent on third-party scripts. Consider auditing which scripts are essential.

Why this matters

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

Google Tag Manager takes 204ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.

Why this matters

This script has high main-thread execution time — optimize hot paths or defer.

Source: web.dev

69% of media.rightmove.co.uk's code is unused. The script may be loading features you don't use.

Why this matters

Bundle has high unused-code ratio — tree-shaking and route-splitting recover the wasted bytes.

Source: web.dev

52% of Google Tag Manager's code is unused. The script may be loading features you don't use.

Why this matters

Bundle has high unused-code ratio — tree-shaking and route-splitting recover the wasted bytes.

Source: web.dev

How third-party costs are calculated

All checks on this page are automated. Results are estimates - run targeted manual reviews when the score affects a release decision.

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