Performance

· 15 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.

SCORE

GRADE

FIX

REVIEW

PASS

INFO

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

Mobile Desktop

Performance

Accessibility

Best Practices

100

SEO

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

340 ms

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

914 ms

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

0 ms

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

0.064

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

1.20 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.

921 ms

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

10 PASS 3 REVIEW

Image Optimization

12 images, 0 KB saveable

REVIEW

12 images, 0 KB saveable

All images are well-optimized

12 images 438 KB

0 oversized -0 KB

7 legacy format

0 missing dimensions CLS risk

JS Bundles

5 scripts, 78 KB unused

REVIEW

5 scripts, 78 KB unused

https://www.bankofengland.co.uk/scripts/boe.vendor...: 39 KB unused (58%)

Consider code splitting or tree shaking to reduce unused code.

https://s.go-mpulse.net/boomerang/9R3WH-S6EDC-8JGQ...: 38 KB unused (66%)

Consider code splitting or tree shaking to reduce unused code.

Total unused JavaScript: 78 KB

78 KB unused JavaScript

Downloaded but never executed on this page.

Script	Size	Unused	Minified	Party
https://www.bankofengland.co.uk/scripts/boe.vendor.min.js?ver=98f91	68 KB	39 KB (58%)	✓	1st
https://s.go-mpulse.net/boomerang/9R3WH-S6EDC-8JGQW-55286-CGTTF	58 KB	38 KB (66%)	✓	3rd
https://www.bankofengland.co.uk/scripts/boe.min.js?ver=98f91	17 KB	—	✓	1st
https://www.bankofengland.co.uk/-/media/css/search-bundle-script.js?ver=BB56DD&mode=npe	27 KB	—	✓	1st
https://www.bankofengland.co.uk/-/media/css/search-new-js.js?ver=6AFCD3&mode=npe	2 KB	—	✓	1st

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

Green Hosting

Action

Whether the site is served from green-energy infrastructure

REVIEW

Green Hosting

No green hosting detected

Page Weight Budget

782 KB transferred, 35 requests

PASS

782 KB transferred, 35 requests

Page weighs 1.7 MB (782 KB transferred)

35 HTTP requests

Estimated 0.16 g CO2 per page load

782 KB transferred

35 requests

0.16 g CO2 per page load

Images 437.8 KiB 56%

JavaScript 171.8 KiB 22%

Fonts 78.9 KiB 10%

CSS 63.0 KiB 8%

Other 15.8 KiB 2%

HTML 14.7 KiB 2%

Other 214 B 0%

0 2.4 MB 4.9 MB

Under budget

A+

Third-Party Impact

7% third-party, 0 ms blocking

PASS

7% third-party, 0 ms blocking

Third-party code accounts for 7% of page weight (58.2 KiB of 782.3 KiB)

Third-party blocking time is low (0 ms)

93%

First-party Third-party

A+

Text Compression

All text resources are compressed

PASS

All text resources are compressed

All text resources are properly compressed.

A+

JS Execution Cost

265ms total JS execution

PASS

265ms total JS execution

https://www.bankofengland.co.uk/: 190ms CPU time

Unattributable: 76ms CPU time

Third-party scripts: 76ms (28% of total)

Main Thread Breakdown

Other 30% Script Evaluation 27% Style & Layout 27% Script Parsing & Compilation 6% Rendering 6% Parse HTML & CSS 5%

Script	Total	Scripting	Parse/Compile	Party
https://www.bankofengland.co.uk/	190ms	23ms	3ms	1st
Unattributable	76ms	2ms	0ms	3rd

A+

Font Loading

2 fonts (79 KB)

PASS

2 fonts (79 KB)

2 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

79 KB total

Render-blocking

of 2

Dominant font-display

swap

Most common across fonts

Font loading timeline

Transfer FOIT (block) FOUT (swap)

GilroyForBOE-Bold.woff woff swap

Size 42 KB

Load time 21 ms

Start 333 ms

Risk FOUT — text flashes from fallback to web font

Convert to woff2 for ~30% smaller file size

GilroyForBOE-Regular.woff2 woff2 swap

Size 37 KB

Load time 25 ms

Start 334 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)

Fixing the unchecked items could save ~13 KB and ~26 ms

A+

Resource Caching

All resources properly cached

PASS

All resources properly cached

No caching issues found

All static resources have appropriate caching headers.

A+

Critical Rendering Path

No render-blocking resources

PASS

No render-blocking resources

No render-blocking resources detected

A+

Resource Hints

No optimization needed

PASS

No optimization needed

No resource hint issues

A+

Page Weight Inventory

35 resources · 782 KB · 78 KB savings available

PASS

35 resources · 782 KB · 78 KB savings available

Within 1MB page-weight target

Got: 782 KB

~78 KB of savings available

16 third-party resources (7% of weight)

1 resources over 200KB

35 resources · 782.3 KiB · 16 third-party Within 1MB page-weight target

Image 58% · 453.6 KiB

JavaScript 22% · 171.8 KiB

Font 10% · 78.9 KiB

CSS 8% · 63.0 KiB

Document 2% · 14.7 KiB

Other 0% · 214 B

~77.6 KiB of savings available

Remove unused JavaScript: 77.6 KiB

#	Resource	Type	Size	Cache	Unused	3rd party	Issues

35 resources			782.3 KiB

HTTP Caching

max-age=60 (1 minute)

PASS

max-age=60 (1 minute)

Cache-Control header is set

Got: max-age=60

Effective TTL: 1 minute (max-age=60)

No ETag or Last-Modified header

Conditional requests (304 Not Modified) are not possible without validators.

Cache-Control

max-age=60

Directive	Value	Meaning
max-age	60	Cache for 1 minute

Effective TTL: 60 seconds

Network Waterfall

35 requests over 814ms

INFO

HTML JavaScript CSS Images Fonts XHR/Fetch Other

Third-Party Script Cost

Per-script blocking time, transfer cost, and cache headers

INFO

28% of JavaScript execution is third-party

First-party Third-party 76ms · 0KB · £1/mo

Script	Category	Execution	Transfer	Unused	Monthly Cost	Verdict
Unattributable Unattributable	Other	76ms	0 KB	—	£1/mo	Optional

Unattributable

Other

Optional

Execution 76ms

Transfer 0 KB

Monthly Cost £1/mo

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.

Browse & Analyze

Learn

Performance

Page Load Progression

Green Hosting

Font loading timeline

Optimization checklist