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Performance

· 17 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
73
GRADE
C
FIX
5
REVIEW
3
PASS
7
INFO
2

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

Mobile Desktop
32
Performance Overall performance score (0–100) based on Core Web Vitals and other metrics. 90+ is good.
97
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.

6.16 s

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

13.95 s

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

1.26 s

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

0.119

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

6.16 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.

14.00 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
17
7 PASS 3 REVIEW 5 FIX
D
Third-Party Impact
Action
100% third-party, 0 ms blocking
FIX
100% third-party, 0 ms blocking
Warning::
Third-party code accounts for 100% of page weight (1.8 MiB of 1.8 MiB)
Info::
Third-party blocking time is low (0 ms)
100%
First-party Third-party
F
JS Execution Cost
Action
3999ms total JS execution
FIX
3999ms total JS execution
Warning::
https://www.lrb.co.uk/lrb_assets/build/js/main.js?...: 1395ms CPU time
Warning::
https://www.lrb.co.uk/: 733ms CPU time
Warning::
https://js.sentry-cdn.com/df903b546d604809adfeedb1...: 486ms CPU time
Warning::
https://www.lrb.co.uk/lrb_assets/build/js/vendor.j...: 345ms CPU time
Warning::
Unattributable: 278ms CPU time
Warning::
Third-party scripts: 3999ms (100% of total)

Main Thread Breakdown

Script Evaluation 56% Style & Layout 16% Other 13% Script Parsing & Compilation 7% Parse HTML & CSS 6%
ScriptTotalScriptingParse/CompileParty
https://www.lrb.co.uk/lrb_assets/build/js/main.js?v=202604161395ms877ms17ms3rd
https://www.lrb.co.uk/733ms165ms6ms3rd
https://js.sentry-cdn.com/df903b546d604809adfeedb11b4f6c10.min.js486ms481ms1ms3rd
https://www.lrb.co.uk/lrb_assets/build/js/vendor.js?v=20260416345ms156ms98ms3rd
Unattributable278ms15ms0ms3rd
https://browser.sentry-cdn.com/10.49.0/bundle.tracing.replay.min.js256ms212ms18ms3rd
https://d.delivery.consentmanager.net/delivery/cmp.php?&cdid=e84d132552193&h=https%3A%2F%2Fwww.lrb.co.uk%2F&&__cmpfcc=1&l=en&ls=EN_EN_EN&lp=EN&o=1776899909739161ms145ms2ms3rd
https://www.gstatic.com/recaptcha/releases/gTpTIWhbKpxADzTzkcabhXN4/recaptcha__en.js149ms82ms66ms3rd
https://www.googletagmanager.com/gtag/js?id=G-JE69ELWJLM121ms80ms39ms3rd
https://cdn.consentmanager.net/delivery/js/cmp_final.min.js?t=2026-4-2275ms38ms34ms3rd
F
JS Bundles
Action
13 scripts, 625 KB unused
FIX
13 scripts, 625 KB unused
Warning::
https://www.gstatic.com/recaptcha/releases/gTpTIWh...: 243 KB unused (67%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.lrb.co.uk/lrb_assets/build/js/vendor.j...: 220 KB unused (74%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.googletagmanager.com/gtag/js?id=G-JE69...: 66 KB unused (38%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://cdn.consentmanager.net/delivery/js/cmp_fin...: 36 KB unused (36%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.lrb.co.uk/lrb_assets/build/js/main.js?...: 31 KB unused (55%)
Consider code splitting or tree shaking to reduce unused code.
Info::
Total unused JavaScript: 625 KB
625 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://www.gstatic.com/recaptcha/releases/gTpTIWhbKpxADzTzkcabhXN4/recaptcha__en.js362 KB243 KB (67%)✓3rd
https://www.lrb.co.uk/lrb_assets/build/js/vendor.js?v=20260416309 KB220 KB (74%)✓3rd
https://www.googletagmanager.com/gtag/js?id=G-JE69ELWJLM172 KB66 KB (38%)✓3rd
https://cdn.consentmanager.net/delivery/js/cmp_final.min.js?t=2026-4-22101 KB36 KB (36%)✓3rd
https://www.lrb.co.uk/lrb_assets/build/js/main.js?v=2026041656 KB31 KB (55%)✓3rd
https://browser.sentry-cdn.com/10.49.0/bundle.tracing.replay.min.js81 KB29 KB (36%)✓3rd
https://js.sentry-cdn.com/df903b546d604809adfeedb11b4f6c10.min.js3 KB—✓3rd
https://cdn.speedcurve.com/js/lux.js?id=434456334911 KB—✓3rd
https://www.google.com/recaptcha/api.js?render=explicit1 KB—✓3rd
https://cdn.consentmanager.net/delivery/customdata/bV8xLndfMTQ0OTIzLnJfR0RQUi5sX2VuLmRfNDcyMzcueF85Mi52LnAudF80NzIzNy54dF8yMzE.js10 KB—✓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
Page Weight Inventory
Action
44 resources · 1.8 MB · 625 KB savings available
FIX
44 resources · 1.8 MB · 625 KB savings available
Warning::
Page weight 819 KB over 1MB target
Got: 1.8 MB Expected: ≤ 1 MB
Info::
~625 KB of savings available
Warning::
43 third-party resources (100% of weight)
Info::
2 resources over 200KB
44 resources · 1.8 MiB · 43 third-party 819.1 KiB over 1MB target
JavaScript 60% · 1.1 MiB
Font 15% · 279.3 KiB
Image 14% · 261.8 KiB
Document 7% · 121.9 KiB
CSS 3% · 63.4 KiB
Other 0% · 6.4 KiB

~625.4 KiB of savings available

Remove unused JavaScript: 625.4 KiB
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.

C
Page Weight Budget
Action
1.8 MB transferred, 44 requests
REVIEW
1.8 MB transferred, 44 requests
Info::
Page weighs 4.7 MB (1.8 MB transferred)
Warning::
JavaScript is 1.1 MB — consider code splitting or lazy loading
Large JavaScript bundles delay interactivity. Split code by route or defer non-critical scripts.
Got: 1.1 MB
Info::
Fonts are 279 KB — consider subsetting or using system fonts
Subset fonts to include only used characters, or switch to system font stacks.
Got: 279 KB
Info::
44 HTTP requests
Info::
Estimated 0.38 g CO2 per page load
1.8 MB / 2.4 MB budget
1.8 MB transferred
44 requests
0.38 g CO2 per page load
JavaScript 1.1 MiB 60%
Fonts 279.3 KiB 15%
Images 259.0 KiB 14%
HTML 120.1 KiB 7%
CSS 63.4 KiB 3%
Other 4.2 KiB 0%
Other 3.0 KiB 0%
Other 2.6 KiB 0%
Other 1.1 KiB 0%
0 2.4 MB 4.9 MB
Approaching limit

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

Subset fonts to include only used characters, or switch to system font stacks.

Why this matters

Font payload is large — subset to used glyphs only, or fall back to system fonts (zero load time).

Source: web.dev font loading

B
Image Optimization
11 images, 0 KB saveable
REVIEW
11 images, 0 KB saveable
Warning::
is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
11 images 259 KB
0 oversized -0 KB
7 legacy format
1 missing dimensions CLS risk

Set explicit width and height to prevent CLS.

Why this matters

Performance issues directly impact user engagement and conversion rates.

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
7 fonts (279 KB)
PASS
7 fonts (279 KB)
Info::
7 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

7

279 KB total

Render-blocking

0

of 7

Dominant font-display

swap

Most common across fonts

Font loading timeline
Transfer FOIT (block) FOUT (swap)
0 ms 2.0 s 4.0 s 6.0 s 8.0 s 10.0 s 12.0 s 14.0 s FCP 6.2 s LCP 14.0 shttps://www.lrb.co.uk/lrb_assets/fonts/IdealSans-Medium.woff2IdealSans-Medium.woff2 https://www.lrb.co.uk/lrb_assets/fonts/IdealSans-Medium.woff2 — 32.7 KiB — 8 ms — font-display: swaphttps://www.lrb.co.uk/lrb_assets/fonts/QuadraatPro.woff2QuadraatPro.woff2 https://www.lrb.co.uk/lrb_assets/fonts/QuadraatPro.woff2 — 50.6 KiB — 7 ms — font-display: swaphttps://www.lrb.co.uk/lrb_assets/fonts/IdealSans-Light.woff2IdealSans-Light.woff2 https://www.lrb.co.uk/lrb_assets/fonts/IdealSans-Light.woff2 — 32.9 KiB — 5 ms — font-display: swaphttps://www.lrb.co.uk/lrb_assets/fonts/IdealSans-Book.woff2IdealSans-Book.woff2 https://www.lrb.co.uk/lrb_assets/fonts/IdealSans-Book.woff2 — 30.1 KiB — 14 ms — font-display: swaphttps://www.lrb.co.uk/lrb_assets/fonts/QuadraatPro-Ita.woff2QuadraatPro-Ita.woff2 https://www.lrb.co.uk/lrb_assets/fonts/QuadraatPro-Ita.woff2 — 47.9 KiB — 8 ms — font-display: swaphttps://www.lrb.co.uk/lrb_assets/fonts/QuadraatPro-Bold.woff2QuadraatPro-Bold.woff2 https://www.lrb.co.uk/lrb_assets/fonts/QuadraatPro-Bold.woff2 — 51.4 KiB — 14 ms — font-display: swaphttps://www.lrb.co.uk/lrb_assets/fonts/IdealSans-LightItalic.woff2IdealSans-LightItalic.w... https://www.lrb.co.uk/lrb_assets/fonts/IdealSans-LightItalic.woff2 — 33.9 KiB — 14 ms — font-display: swap
IdealSans-Medium.woff2 woff2 swap
Size 33 KB
Load time 8 ms
Start 227 ms
Risk FOUT — text flashes from fallback to web font
QuadraatPro.woff2 woff2 swap
Size 51 KB
Load time 7 ms
Start 227 ms
Risk FOUT — text flashes from fallback to web font
IdealSans-Light.woff2 woff2 swap
Size 33 KB
Load time 5 ms
Start 383 ms
Risk FOUT — text flashes from fallback to web font
IdealSans-Book.woff2 woff2 swap
Size 30 KB
Load time 14 ms
Start 386 ms
Risk FOUT — text flashes from fallback to web font
QuadraatPro-Ita.woff2 woff2 swap
Size 48 KB
Load time 8 ms
Start 386 ms
Risk FOUT — text flashes from fallback to web font
QuadraatPro-Bold.woff2 woff2 swap
Size 51 KB
Load time 14 ms
Start 387 ms
Risk FOUT — text flashes from fallback to web font
IdealSans-LightItalic.w... woff2 swap
Size 34 KB
Load time 14 ms
Start 387 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
8 hints, 0 missing preconnects
PASS
8 hints, 0 missing preconnects
Info::
Page uses 8 resource hint(s)

Current Resource Hints

preconnect
3
preload
4
dns-prefetch
1
prefetch
—

8 resource hints configured

A+
Render-Blocking Resources
No render-blocking resources detected
PASS
No render-blocking resources detected
Info::
No render-blocking resources detected in <head>
A+
Third-Party Resources
No third-party resources detected
PASS
No third-party resources detected
Network Waterfall
44 requests over 3380ms
INFO
0 ms 2.0 s 4.0 s 6.0 s 8.0 s 10.0 s 12.0 s 14.0 s FCP 6.2 s LCP 14.0 shttps://lrb.co.uk// https://lrb.co.uk/ — 301 — 265 B — 49 ms — h2https://www.lrb.co.uk/www.lrb.co.uk/ https://www.lrb.co.uk/ — 200 — 119.1 KiB — 186 ms — h2https://www.lrb.co.uk/lrb_assets/build/js/vendor.js?v=20260416www.lrb.co.uk/lrb_assets/build/js/v... https://www.lrb.co.uk/lrb_assets/build/js/vendor.js?v=20260416 — 200 — 309.3 KiB — 228 ms — h2https://www.lrb.co.uk/lrb_assets/build/js/main.js?v=20260416www.lrb.co.uk/lrb_assets/build/js/m... https://www.lrb.co.uk/lrb_assets/build/js/main.js?v=20260416 — 200 — 56.2 KiB — 58 ms — h2https://www.lrb.co.uk/lrb_assets/fonts/IdealSans-Medium.woff2www.lrb.co.uk/lrb_assets/fonts/Idea... https://www.lrb.co.uk/lrb_assets/fonts/IdealSans-Medium.woff2 — 200 — 32.7 KiB — 8 ms — h2https://www.lrb.co.uk/lrb_assets/fonts/QuadraatPro.woff2www.lrb.co.uk/lrb_assets/fonts/Quad... https://www.lrb.co.uk/lrb_assets/fonts/QuadraatPro.woff2 — 200 — 50.6 KiB — 7 ms — h2https://www.lrb.co.uk/lrb_assets/build/css/main.css?v=20260416www.lrb.co.uk/lrb_assets/build/css/... https://www.lrb.co.uk/lrb_assets/build/css/main.css?v=20260416 — 200 — 63.4 KiB — 53 ms — h2https://www.lrb.co.uk/site.webmanifestwww.lrb.co.uk/site.webmanifest https://www.lrb.co.uk/site.webmanifest — 200 — 2.6 KiB — 107 ms — h2https://d.delivery.consentmanager.net/delivery/cmp.php?&cdid=e84d132552193&h=https%3A%2F%2Fwww.lrb.co.uk%2F&&__cmpfcc=1&l=en&ls=EN_EN_EN&lp=EN&o=1776899909739d.delivery.consentmanager.net/deliv... https://d.delivery.consentmanager.net/delivery/cmp.php?&cdid=e84d132552193&h=https%3A%2F%2Fwww.lrb.co.uk%2F&&__cmpfcc=1&l=en&ls=EN_EN_EN&lp=EN&o=1776899909739 — 200 — 2.6 KiB — 144 ms — h2https://cdn.consentmanager.net/delivery/js/cmp_final.min.js?t=2026-4-22cdn.consentmanager.net/delivery/js/... https://cdn.consentmanager.net/delivery/js/cmp_final.min.js?t=2026-4-22 — 200 — 100.9 KiB — 94 ms — h2https://stats.lrb.co.uk/hello.jsstats.lrb.co.uk/hello.js https://stats.lrb.co.uk/hello.js — 200 — 1.9 KiB — 234 ms — h2data:image/svg+xml;charset=utf8,%3Csvg version='1.1' width='17' height='17' baseProfile='tiny' clas…data:image/svg+xml;charset=utf8,%3C... data:image/svg+xml;charset=utf8,%3Csvg version='1.1' width='17' height='17' baseProfile='tiny' clas… — 200 — 0 B — 0 ms — datadata:image/svg+xml;charset=utf-8,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 17 14'%3E%3…www.w3.org/2000/svg' viewBox='0 0 1... data:image/svg+xml;charset=utf-8,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 17 14'%3E%3… — 200 — 0 B — 0 ms — datadata:image/svg+xml;charset=utf-8,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 17 14'%3E%3…www.w3.org/2000/svg' viewBox='0 0 1... data:image/svg+xml;charset=utf-8,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 17 14'%3E%3… — 200 — 0 B — 0 ms — datahttps://www.lrb.co.uk/lrb_assets/build/images/book-icon.2f785f35.svgwww.lrb.co.uk/lrb_assets/build/imag... https://www.lrb.co.uk/lrb_assets/build/images/book-icon.2f785f35.svg — 200 — 880 B — 3 ms — h2data:image/svg+xml;charset=utf8,%3Csvg version='1.1' width='60' height='60' class='backtotopIcon-sv…data:image/svg+xml;charset=utf8,%3C... data:image/svg+xml;charset=utf8,%3Csvg version='1.1' width='60' height='60' class='backtotopIcon-sv… — 200 — 0 B — 0 ms — datahttps://www.lrb.co.uk/lrb_assets/fonts/IdealSans-Light.woff2www.lrb.co.uk/lrb_assets/fonts/Idea... https://www.lrb.co.uk/lrb_assets/fonts/IdealSans-Light.woff2 — 200 — 32.9 KiB — 5 ms — h2https://www.lrb.co.uk/lrb_assets/fonts/IdealSans-Book.woff2www.lrb.co.uk/lrb_assets/fonts/Idea... https://www.lrb.co.uk/lrb_assets/fonts/IdealSans-Book.woff2 — 200 — 30.1 KiB — 14 ms — h2https://www.lrb.co.uk/lrb_assets/fonts/QuadraatPro-Ita.woff2www.lrb.co.uk/lrb_assets/fonts/Quad... https://www.lrb.co.uk/lrb_assets/fonts/QuadraatPro-Ita.woff2 — 200 — 47.9 KiB — 8 ms — h2https://www.lrb.co.uk/lrb_assets/fonts/QuadraatPro-Bold.woff2www.lrb.co.uk/lrb_assets/fonts/Quad... https://www.lrb.co.uk/lrb_assets/fonts/QuadraatPro-Bold.woff2 — 200 — 51.4 KiB — 14 ms — h2https://www.lrb.co.uk/lrb_assets/fonts/IdealSans-LightItalic.woff2www.lrb.co.uk/lrb_assets/fonts/Idea... https://www.lrb.co.uk/lrb_assets/fonts/IdealSans-LightItalic.woff2 — 200 — 33.9 KiB — 14 ms — h2https://cdn.consentmanager.net/delivery/customdata/bV8xLndfMTQ0OTIzLnJfR0RQUi5sX2VuLmRfNDcyMzcueF85Mi52LnAudF80NzIzNy54dF8yMzE.jscdn.consentmanager.net/delivery/cus... https://cdn.consentmanager.net/delivery/customdata/bV8xLndfMTQ0OTIzLnJfR0RQUi5sX2VuLmRfNDcyMzcueF85Mi52LnAudF80NzIzNy54dF8yMzE.js — 200 — 9.5 KiB — 18 ms — h2https://cdn.consentmanager.net/delivery/crossdomain.htmlcdn.consentmanager.net/delivery/cro... https://cdn.consentmanager.net/delivery/crossdomain.html — 200 — 1.0 KiB — 55 ms — h2https://www.lrb.co.uk/lrb_assets/build/images/lrb-monogram-faded.2ae3ec58.svgwww.lrb.co.uk/lrb_assets/build/imag... https://www.lrb.co.uk/lrb_assets/build/images/lrb-monogram-faded.2ae3ec58.svg — 200 — 811 B — 3 ms — h2https://stats.lrb.co.uk/cache?www.lrb.co.ukstats.lrb.co.uk/cache?www.lrb.co.uk https://stats.lrb.co.uk/cache?www.lrb.co.uk — 200 — 50 B — 408 ms — h2https://stats.lrb.co.uk/cache?www.lrb.co.uk/stats.lrb.co.uk/cache?www.lrb.co.uk... https://stats.lrb.co.uk/cache?www.lrb.co.uk/ — 200 — 728 B — 405 ms — h2https://www.lrb.co.uk/data/lrbpwwww.lrb.co.uk/data/lrbpw https://www.lrb.co.uk/data/lrbpw — 200 — 2.4 KiB — 238 ms — h2https://www.lrb.co.uk/lrb_assets/images/icons/lrb-loading.gifwww.lrb.co.uk/lrb_assets/images/ico... https://www.lrb.co.uk/lrb_assets/images/icons/lrb-loading.gif — 200 — 154.2 KiB — 5 ms — h2https://www.lrb.co.uk/customer-number?_=1776899910017www.lrb.co.uk/customer-number?_=177... https://www.lrb.co.uk/customer-number?_=1776899910017 — 200 — 1.0 KiB — 221 ms — h2https://js.sentry-cdn.com/df903b546d604809adfeedb11b4f6c10.min.jsjs.sentry-cdn.com/df903b546d604809a... https://js.sentry-cdn.com/df903b546d604809adfeedb11b4f6c10.min.js — 200 — 2.7 KiB — 48 ms — h2
0 ms 2.0 s 4.0 s 6.0 s 8.0 s 10.0 s 12.0 s 14.0 s FCP 6.2 s LCP 14.0 shttps://lrb.co.uk// https://lrb.co.uk/ — 301 — 265 B — 49 ms — h2https://www.lrb.co.uk/www.lrb.co.uk/ https://www.lrb.co.uk/ — 200 — 119.1 KiB — 186 ms — h2https://www.lrb.co.uk/lrb_assets/build/js/vendor.js?v=20260416www.lrb.co.uk/lrb_assets/build/js/v... https://www.lrb.co.uk/lrb_assets/build/js/vendor.js?v=20260416 — 200 — 309.3 KiB — 228 ms — h2https://www.lrb.co.uk/lrb_assets/build/js/main.js?v=20260416www.lrb.co.uk/lrb_assets/build/js/m... https://www.lrb.co.uk/lrb_assets/build/js/main.js?v=20260416 — 200 — 56.2 KiB — 58 ms — h2https://www.lrb.co.uk/lrb_assets/fonts/IdealSans-Medium.woff2www.lrb.co.uk/lrb_assets/fonts/Idea... https://www.lrb.co.uk/lrb_assets/fonts/IdealSans-Medium.woff2 — 200 — 32.7 KiB — 8 ms — h2https://www.lrb.co.uk/lrb_assets/fonts/QuadraatPro.woff2www.lrb.co.uk/lrb_assets/fonts/Quad... https://www.lrb.co.uk/lrb_assets/fonts/QuadraatPro.woff2 — 200 — 50.6 KiB — 7 ms — 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HTML JavaScript CSS Images Fonts XHR/Fetch Other
Third-Party Script Cost
Per-script blocking time, transfer cost, and cache headers
INFO
100% of JavaScript execution is third-party
First-party Third-party 3999ms · 1206KB · £59/mo
www.lrb.co.uk
Other
Costly
Execution 1395ms
Transfer 56 KB
Unused 55%
Monthly Cost £21/mo
www.lrb.co.uk
Other
Costly
Execution 733ms
Transfer 119 KB
Monthly Cost £11/mo
js.sentry-cdn.com
Other
Costly
Execution 486ms
Transfer 3 KB
Monthly Cost £7/mo
www.lrb.co.uk
Other
Costly
Execution 345ms
Transfer 309 KB
Unused 74%
Monthly Cost £5/mo
Unattributable
Other
Costly
Execution 278ms
Transfer 0 KB
Monthly Cost £4/mo
browser.sentry-cdn.com
Other
Costly
Execution 256ms
Transfer 81 KB
Unused 36%
Monthly Cost £4/mo
d.delivery.consentmanager.net
Other
Optional
Execution 161ms
Transfer 3 KB
Monthly Cost £2/mo
www.gstatic.com
Other
Optional
Execution 149ms
Transfer 362 KB
Unused 67%
Monthly Cost £2/mo
Google Tag Manager
Tag Manager
Optional
Execution 121ms
Transfer 172 KB
Unused 38%
Monthly Cost £2/mo
cdn.consentmanager.net
Other
Optional
Execution 75ms
Transfer 101 KB
Unused 36%
Monthly Cost £1/mo

These scripts may cost more than they're worth

  • www.lrb.co.uk adds 1395ms and costs ~£21/month
  • www.lrb.co.uk adds 733ms and costs ~£11/month
  • js.sentry-cdn.com adds 486ms and costs ~£7/month
  • www.lrb.co.uk adds 345ms and costs ~£5/month
  • Unattributable adds 278ms and costs ~£4/month
  • browser.sentry-cdn.com adds 256ms and costs ~£4/month

100% 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

www.lrb.co.uk takes 1395ms 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

55% of www.lrb.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

www.lrb.co.uk takes 733ms 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

js.sentry-cdn.com takes 486ms 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

www.lrb.co.uk takes 345ms 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

74% of www.lrb.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

Unattributable takes 278ms 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

browser.sentry-cdn.com takes 256ms 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

67% of www.gstatic.com'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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