Performance

· 17 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

100

Best Practices

SEO

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

5.09 s

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

8.03 s

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

167 ms

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

0.674

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

5.28 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.

8.13 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

8 PASS 5 REVIEW 2 FIX

Third-Party Impact

Action

100% third-party, 0 ms blocking

FIX

100% third-party, 0 ms blocking

Third-party code accounts for 100% of page weight (931.2 KiB of 932.0 KiB)

Third-party blocking time is low (0 ms)

100%

First-party Third-party

HTTP Caching

Action

No cache headers

FIX

No cache headers

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.

Image Optimization

Action

18 images, 0 KB saveable

REVIEW

18 images, 0 KB saveable

https://www.bp.com/content/dam/bp/business-sites/e... is missing width/height — may cause layout shift

Set explicit width and height to prevent CLS.

https://www.bp.com/content/dam/bp/business-sites/e... is missing width/height — may cause layout shift

Set explicit width and height to prevent CLS.

18 images 107 KB

0 oversized -0 KB

11 legacy format

2 missing dimensions CLS risk

Set explicit width and height to prevent CLS.

Why this matters

Image without explicit width/height — browser can't reserve space; CLS jumps when image loads.

Source: web.dev / Core Web Vitals

Set explicit width and height to prevent CLS.

Why this matters

Image without explicit width/height — browser can't reserve space; CLS jumps when image loads.

Source: web.dev / Core Web Vitals

JS Execution Cost

Action

1596ms total JS execution

REVIEW

1596ms total JS execution

https://www.bp.com/apps/settings/wcm/designs/refre...: 1001ms CPU time

Unattributable: 342ms CPU time

https://www.bp.com/: 253ms CPU time

Third-party scripts: 1596ms (100% of total)

Main Thread Breakdown

Other 35% Script Evaluation 29% Style & Layout 13% Script Parsing & Compilation 11% Rendering 8% Parse HTML & CSS 4%

Script	Total	Scripting	Parse/Compile	Party
https://www.bp.com/apps/settings/wcm/designs/refresh/bp/assets.js	1001ms	448ms	165ms	3rd
Unattributable	342ms	8ms	0ms	3rd
https://www.bp.com/	253ms	6ms	12ms	3rd

JS Bundles

Action

2 scripts, 251 KB unused

REVIEW

2 scripts, 251 KB unused

https://www.bp.com/apps/settings/wcm/designs/refre...: 251 KB unused (76%)

Consider code splitting or tree shaking to reduce unused code.

Total unused JavaScript: 251 KB

251 KB unused JavaScript

Downloaded but never executed on this page.

Script	Size	Unused	Minified	Party
https://www.bp.com/apps/settings/wcm/designs/refresh/bp/assets.js	330 KB	251 KB (76%)	✓	3rd
https://www.bp.com/etc.clientlibs/clientlibs/granite/jquery/granite/csrf.js	1 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

Page Weight Inventory

31 resources · 932 KB · 251 KB savings available

REVIEW

31 resources · 932 KB · 251 KB savings available

Within 1MB page-weight target

Got: 932 KB

~251 KB of savings available

30 third-party resources (100% of weight)

1 resources over 200KB

31 resources · 932.0 KiB · 30 third-party Within 1MB page-weight target

JavaScript 35% · 330.6 KiB

Font 31% · 284.6 KiB

Document 15% · 143.0 KiB

Image 13% · 123.0 KiB

CSS 5% · 49.6 KiB

Other 0% · 1.1 KiB

~250.8 KiB of savings available

Remove unused JavaScript: 250.8 KiB

#	Resource	Type	Size	Cache	Unused	3rd party	Issues

31 resources			932.0 KiB

Green Hosting

Action

Whether the site is served from green-energy infrastructure

REVIEW

Green Hosting

No green hosting detected

Page Weight Budget

932 KB transferred, 31 requests

PASS

932 KB transferred, 31 requests

Page weighs 2.1 MB (932 KB transferred)

Fonts are 285 KB — consider subsetting or using system fonts

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

Got: 285 KB

31 HTTP requests

Estimated 0.19 g CO2 per page load

932 KB transferred

31 requests

0.19 g CO2 per page load

JavaScript 330.6 KiB 35%

Fonts 284.6 KiB 31%

HTML 141.2 KiB 15%

Images 106.9 KiB 11%

CSS 49.6 KiB 5%

Other 17.9 KiB 2%

Other 1.1 KiB 0%

Other 0 B 0%

0 2.4 MB 4.9 MB

Under budget

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

A+

Text Compression

All text resources are compressed

PASS

All text resources are compressed

All text resources are properly compressed.

A+

Font Loading

4 fonts (285 KB)

PASS

4 fonts (285 KB)

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

Web fonts

285 KB total

Render-blocking

of 4

Dominant font-display

swap

Most common across fonts

Font loading timeline

Transfer FOIT (block) FOUT (swap)

NRIcons.woff2 woff2 swap

Size 7 KB

Load time 32 ms

Start 667 ms

Risk FOUT — text flashes from fallback to web font

Roboto-Regular.woff woff swap

Size 93 KB

Load time 55 ms

Start 668 ms

Risk FOUT — text flashes from fallback to web font

Convert to woff2 for ~30% smaller file size

Roboto-Light.woff woff swap

Size 92 KB

Load time 29 ms

Start 668 ms

Risk FOUT — text flashes from fallback to web font

Convert to woff2 for ~30% smaller file size

Roboto-Bold.woff woff swap

Size 93 KB

Load time 204 ms

Start 668 ms

Risk FOUT — text flashes from fallback to web font

Convert to woff2 for ~30% smaller file size

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 ~83 KB and ~166 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+

Render-Blocking Resources

No render-blocking resources detected

PASS

No render-blocking resources detected

No render-blocking resources detected in <head>

A+

Third-Party Resources

No third-party resources detected

PASS

No third-party resources detected

Network Waterfall

31 requests over 2755ms

INFO

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 1596ms · 471KB · £17/mo

Script	Category	Execution	Transfer	Unused	Monthly Cost	Verdict
www.bp.com www.bp.com	Other	1001ms	330 KB	76%	£10/mo	Costly
Unattributable Unattributable	Other	342ms	0 KB	—	£4/mo	Costly
www.bp.com www.bp.com	Other	253ms	141 KB	—	£3/mo	Costly

www.bp.com

Other

Costly

Execution 1001ms

Transfer 330 KB

Unused 76%

Monthly Cost £10/mo

Unattributable

Other

Costly

Execution 342ms

Transfer 0 KB

Monthly Cost £4/mo

www.bp.com

Other

Costly

Execution 253ms

Transfer 141 KB

Monthly Cost £3/mo

These scripts may cost more than they're worth

www.bp.com adds 1001ms and costs ~£10/month
Unattributable adds 342ms and costs ~£4/month
www.bp.com adds 253ms and costs ~£3/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.bp.com takes 1001ms 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

76% of www.bp.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

Unattributable takes 342ms 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.bp.com takes 253ms 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

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.