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https://simon.com

Performance

· 15 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
85
GRADE
B
FIX
2
REVIEW
4
PASS
7
INFO
2

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

Mobile Desktop
96
Performance Overall performance score (0–100) based on Core Web Vitals and other metrics. 90+ is good.
84
Accessibility Measures how accessible the page is for users with disabilities. Checks color contrast, ARIA labels, and semantic HTML.
81
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.

727 ms

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

1.21 s

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

64 ms

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.

1.16 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.

1.21 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
15
7 PASS 4 REVIEW 2 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 (522.4 KiB of 522.5 KiB)
Info::
Third-party blocking time is low (0 ms)
100%
First-party Third-party
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.

B
JS Execution Cost
955ms total JS execution
REVIEW
955ms total JS execution
Warning::
https://www.simon.com/46SCNLxs/init.js: 569ms CPU time
Warning::
https://www.simon.com/46SCNLxs/captcha/captcha.js?...: 303ms CPU time
Info::
Unattributable: 82ms CPU time
Warning::
Third-party scripts: 955ms (100% of total)

Main Thread Breakdown

Script Evaluation 64% Style & Layout 22% Other 9%
ScriptTotalScriptingParse/CompileParty
https://www.simon.com/46SCNLxs/init.js569ms346ms6ms3rd
https://www.simon.com/46SCNLxs/captcha/captcha.js?a=c&u=d26dd155-3ea3-11f1-9c14-4cf911b6a500&v=&m=0&h=R0VU303ms273ms10ms3rd
Unattributable82ms2ms0ms3rd
C
JS Bundles
Action
8 scripts, 221 KB unused
REVIEW
8 scripts, 221 KB unused
Warning::
https://www.simon.com/46SCNLxs/init.js: 64 KB unused (44%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.simon.com/46SCNLxs/init.js: 64 KB unused (44%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.simon.com/46SCNLxs/captcha/captcha.js?...: 46 KB unused (18%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.simon.com/46SCNLxs/captcha/captcha.js?...: 46 KB unused (18%)
Consider code splitting or tree shaking to reduce unused code.
Info::
Total unused JavaScript: 221 KB
221 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://www.simon.com/46SCNLxs/init.js154 KB64 KB (44%)✓3rd
https://www.simon.com/46SCNLxs/init.js7 KB64 KB (44%)✓3rd
https://www.simon.com/46SCNLxs/captcha/captcha.js?a=c&u=d26dd155-3ea3-11f1-9c14-4cf911b6a500&v=&m=0&h=R0VU271 KB46 KB (18%)✓3rd
https://www.simon.com/46SCNLxs/captcha/captcha.js?a=c&u=d26dd155-3ea3-11f1-9c14-4cf911b6a500&v=&m=0&h=R0VU0 KB46 KB (18%)✓3rd
https://www.simon.com/humanchallengepage.js8 KB—✓3rd
blob:https://www.simon.com/543fc201-c66a-47d2-ab12-151023e5d39e0 KB—✓3rd
blob:https://www.simon.com/af71e3fd-3e80-4a17-b1f8-335d88e67975-0 KB—✓3rd
blob:https://www.simon.com/d1bc64a3-7405-471f-86d5-0300d6b2abdd-0 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

B
Page Weight Inventory
20 resources · 522 KB · 221 KB savings available
REVIEW
20 resources · 522 KB · 221 KB savings available
Info::
Within 1MB page-weight target
Got: 522 KB
Info::
~221 KB of savings available
Warning::
19 third-party resources (100% of weight)
Info::
1 resources over 200KB
20 resources · 522.5 KiB · 19 third-party Within 1MB page-weight target
JavaScript 84% · 440.2 KiB
Font 7% · 36.7 KiB
Image 5% · 25.9 KiB
Document 3% · 13.5 KiB
Other 1% · 3.3 KiB
CSS 1% · 2.9 KiB

~221.5 KiB of savings available

Remove unused JavaScript: 221.5 KiB
C
Green Hosting
Action
Whether the site is served from green-energy infrastructure
REVIEW

Green Hosting

No green hosting detected

A+
Page Weight Budget
522 KB transferred, 20 requests
PASS
522 KB transferred, 20 requests
Info::
Page weighs 1.1 MB (522 KB transferred)
Info::
20 HTTP requests
Info::
Estimated 0.11 g CO2 per page load
522 KB / 2.4 MB budget
522 KB transferred
20 requests
0.11 g CO2 per page load
JavaScript 432.9 KiB 83%
Fonts 36.7 KiB 7%
Images 15.8 KiB 3%
HTML 13.1 KiB 3%
Other 12.0 KiB 2%
Other 9.1 KiB 2%
CSS 2.9 KiB 1%
0 2.4 MB 4.9 MB
Under budget
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+
Image Optimization
1 images, 0 KB saveable
PASS
1 images, 0 KB saveable
Warning::
https://assets.simon.com/content/web/logos/Simon-L... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
1 images 16 KB
0 oversized -0 KB
0 legacy format
1 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

A+
Font Loading
2 fonts (37 KB)
PASS
2 fonts (37 KB)
Info::
2 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

2

37 KB total

Render-blocking

0

of 2

Dominant font-display

swap

Most common across fonts

Font loading timeline
Transfer FOIT (block) FOUT (swap)
0 ms 500 ms 1.0 s FCP 727 ms LCP 1.2 shttps://fonts.gstatic.com/s/roboto/v51/KFO7CnqEu92Fr1ME7kSn66aGLdTylUAMa3yUBHMdazQ.woff2KFO7CnqEu92Fr1ME7kSn66a... https://fonts.gstatic.com/s/roboto/v51/KFO7CnqEu92Fr1ME7kSn66aGLdTylUAMa3yUBHMdazQ.woff2 — 36.7 KiB — 85 ms — font-display: swaphttps://fonts.gstatic.com/s/roboto/v51/KFO7CnqEu92Fr1ME7kSn66aGLdTylUAMa3yUBHMdazQ.woff2KFO7CnqEu92Fr1ME7kSn66a... https://fonts.gstatic.com/s/roboto/v51/KFO7CnqEu92Fr1ME7kSn66aGLdTylUAMa3yUBHMdazQ.woff2 — 0 B — 0 ms — font-display: swap
KFO7CnqEu92Fr1ME7kSn66a... woff2 swap
Size 37 KB
Load time 85 ms
Start 752 ms
Risk FOUT — text flashes from fallback to web font
KFO7CnqEu92Fr1ME7kSn66a... woff2 swap
Size 0 KB
Load time 0 ms
Start 978 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
No optimization needed
PASS
No optimization needed
Info::
No resource hint issues
Network Waterfall
20 requests over 2424ms
INFO
0 ms 500 ms 1.0 s 1.5 s 2.0 s 2.5 s FCP 727 ms LCP 1.2 shttps://simon.com// https://simon.com/ — 301 — 100 B — 293 ms — h2https://www.simon.com/www.simon.com/ https://www.simon.com/ — 307 — 13.1 KiB — 140 ms — h2https://www.simon.com/humanchallengepage.jswww.simon.com/humanchallengepage.js https://www.simon.com/humanchallengepage.js — 200 — 7.9 KiB — 3 ms — h2https://www.simon.com/46SCNLxs/captcha/captcha.js?a=c&u=d26dd155-3ea3-11f1-9c14-4cf911b6a500&v=&m=0&h=R0VUwww.simon.com/46SCNLxs/captcha/capt... https://www.simon.com/46SCNLxs/captcha/captcha.js?a=c&u=d26dd155-3ea3-11f1-9c14-4cf911b6a500&v=&m=0&h=R0VU — 200 — 270.9 KiB — 46 ms — h2https://fonts.googleapis.com/css2?family=Roboto:ital,wght@0,100;0,300;0,400;0,500;0,700;0,900;1,100;1,300;1,400;1,500;1,700;1,900&display=swapfonts.googleapis.com/css2?family=Ro... https://fonts.googleapis.com/css2?family=Roboto:ital,wght@0,100;0,300;0,400;0,500;0,700;0,900;1,100;1,300;1,400;1,500;1,700;1,900&display=swap — 200 — 2.9 KiB — 87 ms — h2https://www.simon.com/46SCNLxs/init.jswww.simon.com/46SCNLxs/init.js https://www.simon.com/46SCNLxs/init.js — 200 — 154.0 KiB — 5 ms — h2https://assets.simon.com/content/web/logos/Simon-Logo.jpgassets.simon.com/content/web/logos/... https://assets.simon.com/content/web/logos/Simon-Logo.jpg — 200 — 15.8 KiB — 4 ms — h2https://tzm.px-cloud.net/ns?c=d26dd155-3ea3-11f1-9c14-4cf911b6a500tzm.px-cloud.net/ns?c=d26dd155-3ea3... https://tzm.px-cloud.net/ns?c=d26dd155-3ea3-11f1-9c14-4cf911b6a500 — 200 — 306 B — 489 ms — http/1.1https://collector-px46scnlxs.px-cloud.net/assets/js/bundlecollector-px46scnlxs.px-cloud.net/a... https://collector-px46scnlxs.px-cloud.net/assets/js/bundle — 200 — 2.2 KiB — 198 ms — h2https://fonts.gstatic.com/s/roboto/v51/KFO7CnqEu92Fr1ME7kSn66aGLdTylUAMa3yUBHMdazQ.woff2fonts.gstatic.com/s/roboto/v51/KFO7... https://fonts.gstatic.com/s/roboto/v51/KFO7CnqEu92Fr1ME7kSn66aGLdTylUAMa3yUBHMdazQ.woff2 — 200 — 36.7 KiB — 85 ms — h3https://www.simon.com/favicon.icowww.simon.com/favicon.ico https://www.simon.com/favicon.ico — 200 — 9.0 KiB — 4 ms — h2blob:https://www.simon.com/543fc201-c66a-47d2-ab12-151023e5d39ewww.simon.com/543fc201-c66a-47d2-ab... blob:https://www.simon.com/543fc201-c66a-47d2-ab12-151023e5d39e — -1 — 0 B — 0 ms — blob:https://www.simon.com/af71e3fd-3e80-4a17-b1f8-335d88e67975www.simon.com/af71e3fd-3e80-4a17-b1... blob:https://www.simon.com/af71e3fd-3e80-4a17-b1f8-335d88e67975 — 200 — -1 B — 1.5 s — blobblob:https://www.simon.com/d1bc64a3-7405-471f-86d5-0300d6b2abddwww.simon.com/d1bc64a3-7405-471f-86... blob:https://www.simon.com/d1bc64a3-7405-471f-86d5-0300d6b2abdd — 200 — -1 B — 1.4 s — blobhttps://fonts.googleapis.com/css2?family=Roboto:ital,wght@0,100;0,300;0,400;0,500;0,700;0,900;1,100;1,300;1,400;1,500;1,700;1,900&display=swapfonts.googleapis.com/css2?family=Ro... https://fonts.googleapis.com/css2?family=Roboto:ital,wght@0,100;0,300;0,400;0,500;0,700;0,900;1,100;1,300;1,400;1,500;1,700;1,900&display=swap — 200 — 0 B — 0 ms — h2https://fonts.gstatic.com/s/roboto/v51/KFO7CnqEu92Fr1ME7kSn66aGLdTylUAMa3yUBHMdazQ.woff2fonts.gstatic.com/s/roboto/v51/KFO7... https://fonts.gstatic.com/s/roboto/v51/KFO7CnqEu92Fr1ME7kSn66aGLdTylUAMa3yUBHMdazQ.woff2 — 200 — 0 B — 0 ms — h3https://www.simon.com/46SCNLxs/captcha/captcha.js?a=c&u=d26dd155-3ea3-11f1-9c14-4cf911b6a500&v=&m=0&h=R0VUwww.simon.com/46SCNLxs/captcha/capt... https://www.simon.com/46SCNLxs/captcha/captcha.js?a=c&u=d26dd155-3ea3-11f1-9c14-4cf911b6a500&v=&m=0&h=R0VU — 200 — 0 B — 2 ms — h2https://www.simon.com/46SCNLxs/init.jswww.simon.com/46SCNLxs/init.js https://www.simon.com/46SCNLxs/init.js — 200 — 7.4 KiB — 3 ms — h2https://collector-px46scnlxs.px-client.net/b/g?payload=aUkQRhAIEHlcZGNRdUVlZWd7DxAeEFYQCEkQeEpVVnpldEp0S2sPEAhGQEdXHhB+SnNkdGVCB3Vxcw8QCBBiagMDBQYHEB4QUXp/eVZYa1RzZ0UPEAgQQkpaURAeEGFwRktqVQNLVwBjDxAIVFNeQVceEHVxQVt+XgN1fkoGDxAIEFdLeAN7WF1baHZ7AGh1Y0p8ZmdGfwBkWn9LAkp/ZWtKfmZeWH9mY0Z8dXxffWZ3SmtYaFp8ZnNFe1tFW1ZbewR7X2NLfF9gWXxYcwJ+Znxea2ZG^/Rn9mdF9i/YQIHa0h3An5lY0VoX2sCf2ZoW39mY0t9YXtBe1xjW319YdwFD8SGsHf3Z3SnxIa0`ap/WGtBe19VW31be0h9ZmhffGZ4WW}tmWlG5oWFVKa1hNm3AH9lYwdoZlUAfWZRS391ZFh/ZWNLaGVgXn91aFhoWHNLaF9nB2hff9F9oZDmhaaFheW3`9YdFO5rAGRbf2ZjAXxles0V7XAIPEB4QfnZWZX9fXlNqVXMPEAhJEGJqAwAFAQoQCAEECx4QYmoDAAUBCxAIAh4QYmoDAAUGAhAIADmh4Q7YmoDAAUGAxAIHwNPHhBWS1p8UGZ0d2B0XQ8QCBBaRkZCQQgdHUVFRRx7BW19dXBxRXV8dEE9Pbw==&appId=PX46SCNLxs&tag=VG9uLRIFfVtQYg==&uuid=d26dd155-3ea3-11f1-9c14-4cf911b6a500&ft=397&seq=1&en=NTA&bi=GwRhS048KWpdXw5uAldSaBoifAwKDiFvFxZ3BiBHIkAUJC90X04icnVQHDAaJWUSGDEkdTMDLShyBmwJVD0+YQgWaTNYB11mWiV1E10WJGoXEn9ndUsrE0gvenYXWWc=&cs=2203a5bb1fb4544f7f45963b4d157201022a313e80c2cd3e434f1c6c9e4f5978&pc=7096713494478201&sid=d2b913ba-3ea3-11f1-8372-12b9d976ba3a%F3%A0%84%B1%F3%A0%84%B7%F3%A0%84%B7%F3%A0%84%B6%F3%A0%84%B9%F3%A0%84%B0%F3%A0%84%B0%F3%A0%84%B8%F3%A0%84%B7%F3%A0%84%B6%F3%A0%84%B1%F3%A0%84%B2%F3%A0%84%B6&vid=d26dd604-3ea3-11f1-9c14-d0ff416b1429&ci=d2bb07e0-3ea3-11f1-9438-f5ad49f9a7b4&pxhd=eDpgd5aRXjb/2HiynVanaM8VfyWdI6cmYTJz7A3e8zvEPyyix93rJ/LY4kqeHVOZ9EPAdNd/Zb-uo48SPuMytg==:LU3p/i/DIReX6N1M9zFSm7ufXmLMvApUJl/LnENEWPUbRd5h3KNAvGSVQgbieBjg2SVNAjVa-cKSeKKn/kNcvV1ZMV236tMffr-jM/6xIU4=&cts=d2b91581-3ea3-11f1-8372-12b9d976ba3a&hid=ohV-wf3vFObXh/025fgGhvmbw7vz6pPQXNXCSTgAVa4=:7kK9RVwMvow3PiohnB86lGrr8cP7x7OtCcN9jwno8h5TnfpSkt9WaOU4eMLc2mLYuc/u8uZvYpStsObuyvadyP8SJnk-dgr2aq-sHs43iA2QaSgYh90YwQonVvEUpLSiqJKj6AqlKAfrHVraeYc5JuLsxd-VE42t0oQe1UkBE5J7a5wdg6JWTzEx0XZ4hJkqcollector-px46scnlxs.px-client.net/... https://collector-px46scnlxs.px-client.net/b/g?payload=aUkQRhAIEHlcZGNRdUVlZWd7DxAeEFYQCEkQeEpVVnpldEp0S2sPEAhGQEdXHhB+SnNkdGVCB3Vxcw8QCBBiagMDBQYHEB4QUXp/eVZYa1RzZ0UPEAgQQkpaURAeEGFwRktqVQNLVwBjDxAIVFNeQVceEHVxQVt+XgN1fkoGDxAIEFdLeAN7WF1baHZ7AGh1Y0p8ZmdGfwBkWn9LAkp/ZWtKfmZeWH9mY0Z8dXxffWZ3SmtYaFp8ZnNFe1tFW1ZbewR7X2NLfF9gWXxYcwJ+Znxea2ZG^/Rn9mdF9i/YQIHa0h3An5lY0VoX2sCf2ZoW39mY0t9YXtBe1xjW319YdwFD8SGsHf3Z3SnxIa0`ap/WGtBe19VW31be0h9ZmhffGZ4WW}tmWlG5oWFVKa1hNm3AH9lYwdoZlUAfWZRS391ZFh/ZWNLaGVgXn91aFhoWHNLaF9nB2hff9F9oZDmhaaFheW3`9YdFO5rAGRbf2ZjAXxles0V7XAIPEB4QfnZWZX9fXlNqVXMPEAhJEGJqAwAFAQoQCAEECx4QYmoDAAUBCxAIAh4QYmoDAAUGAhAIADmh4Q7YmoDAAUGAxAIHwNPHhBWS1p8UGZ0d2B0XQ8QCBBaRkZCQQgdHUVFRRx7BW19dXBxRXV8dEE9Pbw==&appId=PX46SCNLxs&tag=VG9uLRIFfVtQYg==&uuid=d26dd155-3ea3-11f1-9c14-4cf911b6a500&ft=397&seq=1&en=NTA&bi=GwRhS048KWpdXw5uAldSaBoifAwKDiFvFxZ3BiBHIkAUJC90X04icnVQHDAaJWUSGDEkdTMDLShyBmwJVD0+YQgWaTNYB11mWiV1E10WJGoXEn9ndUsrE0gvenYXWWc=&cs=2203a5bb1fb4544f7f45963b4d157201022a313e80c2cd3e434f1c6c9e4f5978&pc=7096713494478201&sid=d2b913ba-3ea3-11f1-8372-12b9d976ba3a%F3%A0%84%B1%F3%A0%84%B7%F3%A0%84%B7%F3%A0%84%B6%F3%A0%84%B9%F3%A0%84%B0%F3%A0%84%B0%F3%A0%84%B8%F3%A0%84%B7%F3%A0%84%B6%F3%A0%84%B1%F3%A0%84%B2%F3%A0%84%B6&vid=d26dd604-3ea3-11f1-9c14-d0ff416b1429&ci=d2bb07e0-3ea3-11f1-9438-f5ad49f9a7b4&pxhd=eDpgd5aRXjb/2HiynVanaM8VfyWdI6cmYTJz7A3e8zvEPyyix93rJ/LY4kqeHVOZ9EPAdNd/Zb-uo48SPuMytg==:LU3p/i/DIReX6N1M9zFSm7ufXmLMvApUJl/LnENEWPUbRd5h3KNAvGSVQgbieBjg2SVNAjVa-cKSeKKn/kNcvV1ZMV236tMffr-jM/6xIU4=&cts=d2b91581-3ea3-11f1-8372-12b9d976ba3a&hid=ohV-wf3vFObXh/025fgGhvmbw7vz6pPQXNXCSTgAVa4=:7kK9RVwMvow3PiohnB86lGrr8cP7x7OtCcN9jwno8h5TnfpSkt9WaOU4eMLc2mLYuc/u8uZvYpStsObuyvadyP8SJnk-dgr2aq-sHs43iA2QaSgYh90YwQonVvEUpLSiqJKj6AqlKAfrHVraeYc5JuLsxd-VE42t0oQe1UkBE5J7a5wdg6JWTzEx0XZ4hJkq — 200 — 1023 B — 203 ms — h2https://collector-px46scnlxs.px-cloud.net/assets/js/bundlecollector-px46scnlxs.px-cloud.net/a... https://collector-px46scnlxs.px-cloud.net/assets/js/bundle — 200 — 1.1 KiB — 162 ms — h2
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 955ms · 7KB · $13/mo
www.simon.com
Other
Costly
Execution 569ms
Transfer 7 KB
Unused 44%
Monthly Cost $8/mo
www.simon.com
Other
Costly
Execution 303ms
Transfer 0 KB
Unused 18%
Monthly Cost $4/mo
Unattributable
Other
Optional
Execution 82ms
Transfer 0 KB
Monthly Cost $1/mo

These scripts may cost more than they're worth

  • www.simon.com adds 569ms and costs ~$8/month
  • www.simon.com adds 303ms 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.simon.com takes 569ms 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.simon.com takes 303ms 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

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