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Performance

· 16 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
70
GRADE
C
FIX
4
REVIEW
3
PASS
7
INFO
2

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

Mobile Desktop
43
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.

2.61 s

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

8.19 s

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

607 ms

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

0.133

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

9.12 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.

24.51 s

Page Load Progression

433 ms
866 ms
1.3 s
1.7 s
2.2 s
2.6 s
3.0 s
3.5 s
Checks
16
7 PASS 3 REVIEW 4 FIX
F
Page Weight Budget
Action
5.3 MB transferred, 178 requests
FIX
5.3 MB transferred, 178 requests
Critical::
Page weighs 10.2 MB (5.3 MB transferred)
Warning::
Images are 3.1 MB — compress or use modern formats
Convert images to WebP/AVIF and resize to display dimensions to reduce transfer size.
Got: 3.1 MB
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::
Fonts are 367 KB — consider subsetting or using system fonts
Subset fonts to include only used characters, or switch to system font stacks.
Got: 367 KB
Warning::
178 HTTP requests — consider bundling or reducing
Each request adds latency. Bundle small files, use sprites, or eliminate unnecessary requests.
Info::
Estimated 1.1 g CO2 per page load
5.3 MB / 2.4 MB budget
5.3 MB transferred
178 requests
1.1 g CO2 per page load
Images 3.1 MiB 59%
JavaScript 1.6 MiB 30%
Fonts 366.9 KiB 7%
HTML 138.1 KiB 3%
CSS 54.1 KiB 1%
Other 30.0 KiB 1%
Other 13.4 KiB 0%
Other 3.8 KiB 0%
Other 685 B 0%
Other 0 B 0%
0 2.4 MB 4.9 MB
Over budget

Convert images to WebP/AVIF and resize to display dimensions to reduce transfer size.

Why this matters

Image bandwidth is high — modern formats (WebP/AVIF) and resizing typically cut it 50%+.

Source: web.dev

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

Each request adds latency. Bundle small files, use sprites, or eliminate unnecessary requests.

Why this matters

High HTTP request count — bundling, sprite-ing, and HTTP/2 server push can reduce per-request overhead.

Source: web.dev

D
Third-Party Impact
Action
64% third-party, 0 ms blocking
FIX
64% third-party, 0 ms blocking
Warning::
Third-party code accounts for 64% of page weight (3.4 MiB of 5.3 MiB)
Info::
Third-party blocking time is low (0 ms)
36%
64%
First-party Third-party
F
JS Execution Cost
Action
7670ms total JS execution
FIX
7670ms total JS execution
Warning::
https://www.formula1.com/: 2738ms CPU time
Warning::
Unattributable: 1469ms CPU time
Warning::
https://www.formula1.com/assets/home/_next/static/...: 846ms CPU time
Warning::
https://www.formula1.com/assets/home/_next/static/...: 473ms CPU time
Warning::
https://www.googletagmanager.com/gtm.js?id=GTM-NTR...: 389ms CPU time
Info::
Third-party scripts: 3096ms (40% of total)

Main Thread Breakdown

Script Evaluation 29% Other 29% Style & Layout 22% Rendering 9% Script Parsing & Compilation 8%
ScriptTotalScriptingParse/CompileParty
https://www.formula1.com/2738ms21ms73ms1st
Unattributable1469ms14ms0ms3rd
https://www.formula1.com/assets/home/_next/static/chunks/528-bc7c2743f4f9dae5.js846ms716ms16ms1st
https://www.formula1.com/assets/home/_next/static/chunks/785-aa4f3c926a14e678.js473ms337ms135ms1st
https://www.googletagmanager.com/gtm.js?id=GTM-NTR4PPW389ms266ms61ms3rd
https://www.formula1.com/assets/home/_next/static/chunks/74-1b0ad625aae7b57b.js366ms13ms24ms1st
https://consent.formula1.com/Notice.8f529.js324ms266ms32ms3rd
https://consent.formula1.com/unified/wrapperMessagingWithoutDetection.js230ms141ms10ms3rd
https://securepubads.g.doubleclick.net/pagead/managed/js/gpt/m202604020101/pubads_impl.js194ms119ms68ms3rd
https://www.googletagmanager.com/gtm.js?id=GTM-K8R56M6&l=dataLayer193ms137ms55ms3rd

Showing top 10 of 15 scripts

F
JS Bundles
Action
22 scripts, 937 KB unused
FIX
22 scripts, 937 KB unused
Warning::
https://www.formula1.com/assets/home/_next/static/...: 342 KB unused (80%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://securepubads.g.doubleclick.net/pagead/mana...: 141 KB unused (77%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.formula1.com/assets/home/_next/static/...: 140 KB unused (83%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.googletagmanager.com/gtm.js?id=GTM-K8R...: 82 KB unused (50%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://consent.formula1.com/Notice.8f529.js: 62 KB unused (69%)
Consider code splitting or tree shaking to reduce unused code.
Info::
Total unused JavaScript: 937 KB
937 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://www.formula1.com/assets/home/_next/static/chunks/785-aa4f3c926a14e678.js433 KB342 KB (80%)✓1st
https://securepubads.g.doubleclick.net/pagead/managed/js/gpt/m202604020101/pubads_impl.js183 KB141 KB (77%)✓3rd
https://www.formula1.com/assets/home/_next/static/chunks/b44ffc44-5babc187430cb039.js170 KB140 KB (83%)✓1st
https://www.googletagmanager.com/gtm.js?id=GTM-K8R56M6&l=dataLayer164 KB82 KB (50%)✓3rd
https://consent.formula1.com/Notice.8f529.js91 KB62 KB (69%)✓3rd
https://www.formula1.com/assets/home/_next/static/chunks/6bdcba90-4f94600a7a96a195.js76 KB61 KB (82%)✓1st
https://www.formula1.com/assets/home/_next/static/chunks/74-1b0ad625aae7b57b.js87 KB54 KB (63%)✓1st
https://www.googletagmanager.com/gtm.js?id=GTM-NTR4PPW163 KB53 KB (33%)✓3rd
https://code.jquery.com/jquery-3.7.1.slim.min.js24 KB—✓3rd
https://www.googletagservices.com/tag/js/gpt.js34 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

C
Image Optimization
Action
123 images, 0 KB saveable
REVIEW
123 images, 0 KB saveable
Warning::
https://www.formula1.com/assets/home/_next/static/... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.formula1.com/assets/home/_next/static/... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.formula1.com/assets/home/_next/static/... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
123 images 3.1 MB
0 oversized -0 KB
17 legacy format
3 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

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

C
Green Hosting
Action
Whether the site is served from green-energy infrastructure
REVIEW

Green Hosting

No green hosting detected

B
HTTP Caching
max-age=0, s-maxage=60, stale-while-revalidate=300, stale-if-error=86400
REVIEW
max-age=0, s-maxage=60, stale-while-revalidate=300, stale-if-error=86400
Info::
Cache-Control header is set
Got: max-age=0, s-maxage=60, stale-while-revalidate=300, stale-if-error=86400
Info::
CDN TTL: 1 minute (s-maxage=60)
Info::
No ETag or Last-Modified header
Conditional requests (304 Not Modified) are not possible without validators.
Cache-Control

max-age=0, s-maxage=60, stale-while-revalidate=300, stale-if-error=86400

DirectiveValueMeaning
max-age0Cache for 0 seconds
s-maxage60CDN caches for 1 minute
stale-while-revalidate300Serve stale for 5 minutes while fetching fresh
stale-if-error86400
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
12 fonts (367 KB)
PASS
12 fonts (367 KB)
Info::
12 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

12

367 KB total

Render-blocking

0

of 12

Dominant font-display

swap

Most common across fonts

Font loading timeline
Transfer FOIT (block) FOUT (swap)
0 ms 1.0 s 2.0 s 3.0 s 4.0 s 5.0 s 6.0 s 7.0 s 8.0 s FCP 2.6 s LCP 8.2 shttps://www.formula1.com/s/fonts/titillium/TitilliumWeb-Bold.ttfTitilliumWeb-Bold.ttf https://www.formula1.com/s/fonts/titillium/TitilliumWeb-Bold.ttf — 53.2 KiB — 0 ms — font-display: swaphttps://www.formula1.com/s/fonts/formula1/Formula1-Regular.woff2Formula1-Regular.woff2 https://www.formula1.com/s/fonts/formula1/Formula1-Regular.woff2 — 25.0 KiB — 0 ms — font-display: swaphttps://www.formula1.com/s/fonts/titillium/TitilliumWeb-Regular.ttfTitilliumWeb-Regular.ttf https://www.formula1.com/s/fonts/titillium/TitilliumWeb-Regular.ttf — 56.6 KiB — 0 ms — font-display: swaphttps://www.formula1.com/s/fonts/formula1/Formula1-Black.woff2Formula1-Black.woff2 https://www.formula1.com/s/fonts/formula1/Formula1-Black.woff2 — 26.8 KiB — 0 ms — font-display: swaphttps://www.formula1.com/s/fonts/titillium/TitilliumWeb-SemiBold.ttfTitilliumWeb-SemiBold.ttf https://www.formula1.com/s/fonts/titillium/TitilliumWeb-SemiBold.ttf — 55.9 KiB — 0 ms — font-display: swaphttps://www.formula1.com/s/fonts/formula1/Formula1-Bold.woff2Formula1-Bold.woff2 https://www.formula1.com/s/fonts/formula1/Formula1-Bold.woff2 — 25.3 KiB — 0 ms — font-display: swaphttps://www.formula1.com/s/fonts/kh-interference-f1/KHInterferenceF1-Bold.woff2KHInterferenceF1-Bold.w... https://www.formula1.com/s/fonts/kh-interference-f1/KHInterferenceF1-Bold.woff2 — 21.0 KiB — 0 ms — font-display: swaphttps://www.formula1.com/s/fonts/apax-th/Apax-TAG-Heuer-Regular.woff2Apax-TAG-Heuer-Regular.... https://www.formula1.com/s/fonts/apax-th/Apax-TAG-Heuer-Regular.woff2 — 34.4 KiB — 0 ms — font-display: swaphttps://www.formula1.com/s/fonts/kh-interference-f1/KHInterferenceF1-Regular.woff2KHInterferenceF1-Regula... https://www.formula1.com/s/fonts/kh-interference-f1/KHInterferenceF1-Regular.woff2 — 20.0 KiB — 0 ms — font-display: swaphttps://www.formula1.com/etc/designs/fom-website/fonts/F1Regular/Formula1-Regular.woff2Formula1-Regular.woff2 https://www.formula1.com/etc/designs/fom-website/fonts/F1Regular/Formula1-Regular.woff2 — 25.1 KiB — 0 ms — font-display: swaphttps://fonts.gstatic.com/s/titilliumweb/v19/NaPecZTIAOhVxoMyOr9n_E7fdMPmDaZRbrw.woff2NaPecZTIAOhVxoMyOr9n_E7... https://fonts.gstatic.com/s/titilliumweb/v19/NaPecZTIAOhVxoMyOr9n_E7fdMPmDaZRbrw.woff2 — 12.1 KiB — 0 ms — font-display: swaphttps://fonts.gstatic.com/s/titilliumweb/v19/NaPDcZTIAOhVxoMyOr9n_E7ffHjDGItzY5abuWI.woff2NaPDcZTIAOhVxoMyOr9n_E7... https://fonts.gstatic.com/s/titilliumweb/v19/NaPDcZTIAOhVxoMyOr9n_E7ffHjDGItzY5abuWI.woff2 — 11.5 KiB — 0 ms — font-display: swap
TitilliumWeb-Bold.ttf ttf swap
Size 53 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
  • Convert to woff2 for ~30% smaller file size
Formula1-Regular.woff2 woff2 swap
Size 25 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
TitilliumWeb-Regular.ttf ttf swap
Size 57 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
  • Convert to woff2 for ~30% smaller file size
Formula1-Black.woff2 woff2 swap
Size 27 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
TitilliumWeb-SemiBold.ttf ttf swap
Size 56 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
  • Convert to woff2 for ~30% smaller file size
Formula1-Bold.woff2 woff2 swap
Size 25 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
KHInterferenceF1-Bold.w... woff2 swap
Size 21 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
Apax-TAG-Heuer-Regular.... woff2 swap
Size 34 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
KHInterferenceF1-Regula... woff2 swap
Size 20 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
Formula1-Regular.woff2 woff2 swap
Size 25 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
NaPecZTIAOhVxoMyOr9n_E7... woff2 swap
Size 12 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
NaPDcZTIAOhVxoMyOr9n_E7... woff2 swap
Size 11 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)

Fixing the unchecked items could save ~50 KB and ~100 ms

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
103 hints, 0 missing preconnects
PASS
103 hints, 0 missing preconnects
Info::
Page uses 103 resource hint(s)

Current Resource Hints

preconnect
—
preload
+93
103
dns-prefetch
—
prefetch
—

103 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
178 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
40% of JavaScript execution is third-party
First-party Third-party 3096ms · 707KB · $41/mo
Unattributable
Other
Costly
Execution 1469ms
Transfer 0 KB
Monthly Cost $20/mo
Google Tag Manager
Tag Manager
Costly
Execution 389ms
Transfer 163 KB
Unused 33%
Monthly Cost $5/mo
consent.formula1.com
Other
Costly
Execution 324ms
Transfer 91 KB
Unused 69%
Monthly Cost $4/mo
consent.formula1.com
Other
Costly
Execution 230ms
Transfer 40 KB
Monthly Cost $3/mo
securepubads.g.doubleclick.net
Other
Optional
Execution 194ms
Transfer 183 KB
Unused 77%
Monthly Cost $3/mo
Google Tag Manager
Tag Manager
Optional
Execution 193ms
Transfer 164 KB
Unused 50%
Monthly Cost $3/mo
consent.formula1.com
Other
Optional
Execution 119ms
Transfer 2 KB
Monthly Cost $2/mo
www.googletagservices.com
Other
Optional
Execution 106ms
Transfer 34 KB
Monthly Cost $1/mo
consent.formula1.com
Other
Optional
Execution 72ms
Transfer 29 KB
Monthly Cost $1/mo

These scripts may cost more than they're worth

  • Unattributable adds 1469ms and costs ~$20/month
  • Google Tag Manager adds 389ms and costs ~$5/month
  • consent.formula1.com adds 324ms and costs ~$4/month
  • consent.formula1.com adds 230ms and costs ~$3/month

40% of JavaScript execution time comes from third-party scripts.

Why this matters

Third-party scripts (analytics, ads, social, A/B testing) often dominate execution time — every one is a perf-and-privacy tax.

Learn more ▾

Each third-party script is a black box: you don't control when it loads, what it executes, or how much it grows. They often account for a major share of total blocking time on average sites (HTTP Archive's Web Almanac documents the trend). Audit which ones you actually need, defer the rest, and use facade patterns (lite-youtube, lite-vimeo) for embedded media.

Source: web.dev / HTTP Archive Web Almanac

Unattributable takes 1469ms 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

Google Tag Manager takes 389ms 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

consent.formula1.com takes 324ms 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 consent.formula1.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

consent.formula1.com takes 230ms 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

77% of securepubads.g.doubleclick.net'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

50% 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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