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Performance

· 16 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
74
GRADE
C
FIX
5
REVIEW
2
PASS
7
INFO
2

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

Mobile Desktop
34
Performance Overall performance score (0–100) based on Core Web Vitals and other metrics. 90+ is good.
95
Accessibility Measures how accessible the page is for users with disabilities. Checks color contrast, ARIA labels, and semantic HTML.
100
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.

4.57 s

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

17.12 s

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

1.29 s

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

0.000

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

7.52 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.

17.23 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
16
7 PASS 2 REVIEW 5 FIX
F
Page Weight Budget
Action
2.9 MB transferred, 60 requests
FIX
2.9 MB transferred, 60 requests
Warning::
Page weighs 6.7 MB (2.9 MB transferred)
Warning::
JavaScript is 1.3 MB — consider code splitting or lazy loading
Large JavaScript bundles delay interactivity. Split code by route or defer non-critical scripts.
Got: 1.3 MB
Warning::
Images are 1.2 MB — compress or use modern formats
Convert images to WebP/AVIF and resize to display dimensions to reduce transfer size.
Got: 1.2 MB
Info::
60 HTTP requests
Info::
Estimated 0.61 g CO2 per page load
2.9 MB / 2.4 MB budget
2.9 MB transferred
60 requests
0.61 g CO2 per page load
JavaScript 1.3 MiB 46%
Images 1.2 MiB 42%
HTML 128.1 KiB 4%
Fonts 127.6 KiB 4%
Other 62.7 KiB 2%
CSS 49.6 KiB 2%
Other 1.8 KiB 0%
Other 884 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

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

D
Third-Party Impact
Action
93% third-party, 0 ms blocking
FIX
93% third-party, 0 ms blocking
Warning::
Third-party code accounts for 93% of page weight (2.7 MiB of 2.9 MiB)
Info::
Third-party blocking time is low (0 ms)
93%
First-party Third-party
F
JS Execution Cost
Action
4421ms total JS execution
FIX
4421ms total JS execution
Warning::
https://www.strava.com/: 962ms CPU time
Warning::
https://web-assets.strava.com/assets/landing-pages...: 814ms CPU time
Warning::
https://web-assets.strava.com/assets/landing-pages...: 570ms CPU time
Warning::
Unattributable: 521ms CPU time
Warning::
https://consent.cookiebot.com/uc.js: 384ms CPU time
Warning::
Third-party scripts: 3458ms (78% of total)

Main Thread Breakdown

Script Evaluation 47% Other 20% Style & Layout 10% Script Parsing & Compilation 9% Rendering 8% Parse HTML & CSS 4%
ScriptTotalScriptingParse/CompileParty
https://www.strava.com/962ms5ms1ms1st
https://web-assets.strava.com/assets/landing-pages/_next/static/chunks/pages/_app-090d844577d2f000.js814ms571ms152ms3rd
https://web-assets.strava.com/assets/landing-pages/_next/static/chunks/framework-7f9d59fd7074d9f7.js570ms485ms15ms3rd
Unattributable521ms36ms0ms3rd
https://consent.cookiebot.com/uc.js384ms213ms11ms3rd
https://www.googletagmanager.com/gtag/js?id=G-ESZ0QKJW56&l=googleTagManagerDataLayer&cx=c&gtm=4e6460343ms293ms46ms3rd
https://www.googletagmanager.com/gtm.js?id=GTM-TP845S&l=googleTagManagerDataLayer189ms142ms45ms3rd
https://appleid.cdn-apple.com/appleauth/static/jsapi/appleid/1/en_US/appleid.auth.js183ms7ms4ms3rd
https://web-assets.strava.com/assets/landing-pages/_next/static/chunks/main-6f5274bcc70697b8.js171ms156ms14ms3rd
https://web-assets.strava.com/assets/landing-pages/_next/static/chunks/pages/index-c53ced12e67e5d8f.js166ms161ms5ms3rd

Showing top 10 of 11 scripts

F
JS Bundles
Action
20 scripts, 570 KB unused
FIX
20 scripts, 570 KB unused
Warning::
https://web-assets.strava.com/assets/landing-pages...: 256 KB unused (58%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://web-assets.strava.com/assets/landing-pages...: 72 KB unused (80%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.googletagmanager.com/gtm.js?id=GTM-TP8...: 72 KB unused (44%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.googletagmanager.com/gtag/js?id=G-ESZ0...: 63 KB unused (36%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.googletagmanager.com/gtag/js?id=DC-150...: 63 KB unused (49%)
Consider code splitting or tree shaking to reduce unused code.
Info::
Total unused JavaScript: 570 KB
570 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://web-assets.strava.com/assets/landing-pages/_next/static/chunks/pages/_app-090d844577d2f000.js440 KB256 KB (58%)✓3rd
https://web-assets.strava.com/assets/landing-pages/_next/static/chunks/59947-2e0be482d37a1813.js91 KB72 KB (80%)✓3rd
https://www.googletagmanager.com/gtm.js?id=GTM-TP845S&l=googleTagManagerDataLayer165 KB72 KB (44%)✓3rd
https://www.googletagmanager.com/gtag/js?id=G-ESZ0QKJW56&l=googleTagManagerDataLayer&cx=c&gtm=4e6460174 KB63 KB (36%)✓3rd
https://www.googletagmanager.com/gtag/js?id=DC-15023759&l=googleTagManagerDataLayer&cx=c&gtm=4e6460129 KB63 KB (49%)✓3rd
https://consent.cookiebot.com/uc.js36 KB22 KB (63%)✓3rd
https://web-assets.strava.com/assets/landing-pages/_next/static/chunks/main-6f5274bcc70697b8.js39 KB21 KB (54%)✓3rd
https://web-assets.strava.com/assets/landing-pages/_next/static/chunks/33389-81b68a47342e3051.js44 KB—✓3rd
https://web-assets.strava.com/assets/landing-pages/_next/static/chunks/38247-4c5e6f845bd4b713.js11 KB—✓3rd
https://web-assets.strava.com/assets/landing-pages/_next/static/chunks/54780-b89ac63af46500f9.js22 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

D
HTTP Caching
Action
no-store (uncacheable)
FIX
no-store (uncacheable)
Info::
Cache-Control: no-store prevents all caching
Intentional for dynamic content, but increases server load for every page view.
Got: private, no-cache, no-store, max-age=0, must-revalidate
Info::
ETag present — enables conditional (304) responses
Cache-Control

private, no-cache, no-store, max-age=0, must-revalidate

DirectiveValueMeaning
private—Only browser cache, not CDN/proxy
no-cache—Cache but always revalidate first
no-store—Never cache this response
max-age0Cache for 0 seconds
must-revalidate—Must recheck with server after expiry
B
Image Optimization
20 images, 0 KB saveable
REVIEW
20 images, 0 KB saveable
Info::
All images are well-optimized
20 images 1.2 MB
0 oversized -0 KB
17 legacy format
0 missing dimensions CLS risk
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
3 fonts (128 KB)
PASS
3 fonts (128 KB)
Info::
3 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

3

128 KB total

Render-blocking

0

of 3

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 16.0 s FCP 4.6 s LCP 17.1 shttps://strava-web-assets.s3.amazonaws.com/assets/fonts/Boathouse/Static/Boathouse-Regular.woff2Boathouse-Regular.woff2 https://strava-web-assets.s3.amazonaws.com/assets/fonts/Boathouse/Static/Boathouse-Regular.woff2 — 41.8 KiB — 0 ms — font-display: swaphttps://strava-web-assets.s3.amazonaws.com/assets/fonts/Boathouse/Static/Boathouse-Medium.woff2Boathouse-Medium.woff2 https://strava-web-assets.s3.amazonaws.com/assets/fonts/Boathouse/Static/Boathouse-Medium.woff2 — 42.0 KiB — 0 ms — font-display: swaphttps://strava-web-assets.s3.amazonaws.com/assets/fonts/Boathouse/Static/Boathouse-Regular-Oblique.woff2Boathouse-Regular-Obliq... https://strava-web-assets.s3.amazonaws.com/assets/fonts/Boathouse/Static/Boathouse-Regular-Oblique.woff2 — 43.7 KiB — 0 ms — font-display: swap
Boathouse-Regular.woff2 woff2 swap
Size 42 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
Boathouse-Medium.woff2 woff2 swap
Size 42 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
Boathouse-Regular-Obliq... woff2 swap
Size 44 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
6 hints, 0 missing preconnects
PASS
6 hints, 0 missing preconnects
Info::
Page uses 6 resource hint(s)

Current Resource Hints

preconnect
—
preload
6
dns-prefetch
—
prefetch
—

6 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
60 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
78% of JavaScript execution is third-party
First-party Third-party 3458ms · 1058KB · €55/mo
web-assets.strava.com
Other
Costly
Execution 814ms
Transfer 440 KB
Unused 58%
Monthly Cost €13/mo
web-assets.strava.com
Other
Costly
Execution 570ms
Transfer 45 KB
Monthly Cost €9/mo
Unattributable
Other
Costly
Execution 521ms
Transfer 0 KB
Monthly Cost €8/mo
consent.cookiebot.com
Other
Costly
Execution 384ms
Transfer 36 KB
Unused 63%
Monthly Cost €6/mo
Google Tag Manager
Tag Manager
Costly
Execution 343ms
Transfer 174 KB
Unused 36%
Monthly Cost €5/mo
Google Tag Manager
Tag Manager
Optional
Execution 189ms
Transfer 165 KB
Unused 44%
Monthly Cost €3/mo
appleid.cdn-apple.com
Other
Optional
Execution 183ms
Transfer 17 KB
Monthly Cost €3/mo
web-assets.strava.com
Other
Optional
Execution 171ms
Transfer 39 KB
Unused 54%
Monthly Cost €3/mo
web-assets.strava.com
Other
Optional
Execution 166ms
Transfer 12 KB
Monthly Cost €3/mo
Google Tag Manager
Tag Manager
Optional
Execution 119ms
Transfer 129 KB
Unused 49%
Monthly Cost €2/mo

These scripts may cost more than they're worth

  • web-assets.strava.com adds 814ms and costs ~€13/month
  • web-assets.strava.com adds 570ms and costs ~€9/month
  • Unattributable adds 521ms and costs ~€8/month
  • consent.cookiebot.com adds 384ms and costs ~€6/month
  • Google Tag Manager adds 343ms and costs ~€5/month

78% 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

web-assets.strava.com takes 814ms 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

58% of web-assets.strava.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

web-assets.strava.com takes 570ms 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

Unattributable takes 521ms 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.cookiebot.com takes 384ms 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

63% of consent.cookiebot.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

Google Tag Manager takes 343ms 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

54% of web-assets.strava.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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