Performance
· 17 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.Performance-focused optimization plan with CWV assessment, top offenders, and time estimates
First Contentful Paint First Contentful Paint — how long until the browser renders the first piece of content. Under 1.8s is good.
2.80 s
Largest Contentful Paint Largest Contentful Paint — how long until the largest visible element loads. Under 2.5s is good.
3.75 s
Total Blocking Time Total Blocking Time — total time the main thread was blocked, preventing user input. Under 200ms is good.
10.63 s
Cumulative Layout Shift Cumulative Layout Shift — measures visual stability. How much the page layout shifts during loading. Under 0.1 is good.
0.055
Speed Index Speed Index — how quickly content is visually displayed during load. Under 3.4s is good.
10.86 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.
48.95 s
Page Load Progression
FPage Weight BudgetAction4.6 MB transferred, 469 requestsFIX
Large JavaScript bundles delay interactivity. Split code by route or defer non-critical scripts.
JavaScript bundle is large — code-split routes and lazy-load off-screen components to defer.
Source: web.dev
Each request adds latency. Bundle small files, use sprites, or eliminate unnecessary requests.
High HTTP request count — bundling, sprite-ing, and HTTP/2 server push can reduce per-request overhead.
Source: web.dev
DThird-Party ImpactAction100% third-party, 0 ms blockingFIX
FJS Execution CostAction31037ms total JS executionFIX
Main Thread Breakdown
| Script | Total | Scripting | Parse/Compile | Party |
|---|---|---|---|---|
| https://www.cars.com/ | 5694ms | 110ms | 6ms | 3rd |
| https://www.cars.com/static/js/common.fc2a09d8fa23803a33b7.js?vsn=d | 4470ms | 3321ms | 105ms | 3rd |
| Unattributable | 3166ms | 604ms | 0ms | 3rd |
| https://securepubads.g.doubleclick.net/pagead/managed/js/gpt/m202604160201/pubads_impl.js | 2508ms | 1495ms | 72ms | 3rd |
| https://www.cars.com/8DPpMTkZ/t8G/Oe9/FFucx1oD7K/YrLYcQG2rQp8hGub/ORoxZ2Ms/LiAOb/HY0ISAB | 1154ms | 1068ms | 53ms | 3rd |
| https://www.googletagmanager.com/gtag/js?id=AW-1069770364&cx=c>m=4e64k0h1 | 758ms | 599ms | 47ms | 3rd |
| https://www.googletagmanager.com/gtm.js?id=GTM-TMPDK9X | 748ms | 631ms | 85ms | 3rd |
| https://c.aaxads.com/aax.js?pub=AAX42WKKE&hst=www.cars.com&ver=aax.ver | 748ms | 289ms | 9ms | 3rd |
| https://wsv3cdn.audioeye.com/static-scripts/v2/2026-04-22/startup.bundle.js | 739ms | 529ms | 54ms | 3rd |
| https://scripts.clarity.ms/0.8.60-beta/clarity.js | 739ms | 405ms | 12ms | 3rd |
Showing top 10 of 56 scripts
FJS BundlesAction131 scripts, 1.1 MB unusedFIX
Downloaded but never executed on this page.
| Script | Size | Unused | Minified | Party |
|---|---|---|---|---|
| https://securepubads.g.doubleclick.net/pagead/managed/js/gpt/m202604160201/pubads_impl.js | 188 KB | 88 KB (47%) | ✓ | 3rd |
| https://accounts.google.com/gsi/client | 96 KB | 68 KB (71%) | ✓ | 3rd |
| https://wsv3cdn.audioeye.com/static-scripts/v2/2026-04-22/startup.bundle.js | 124 KB | 65 KB (53%) | ✓ | 3rd |
| https://www.googletagmanager.com/gtag/js?id=G-0SVYF8BFF1&cx=c>m=4e64k0h1 | 161 KB | 64 KB (40%) | ✓ | 3rd |
| https://www.cars.com/static/js/common.fc2a09d8fa23803a33b7.js?vsn=d | 144 KB | 62 KB (43%) | ✓ | 3rd |
| https://www.googletagmanager.com/gtag/js?id=DC-4235921&cx=c>m=4e64k0h1 | 130 KB | 61 KB (47%) | ✓ | 3rd |
| https://analytics.tiktok.com/i18n/pixel/static/main.MWE0ZWQ3ZWQwMA.js | 106 KB | 60 KB (57%) | ✓ | 3rd |
| https://cdn.cookielaw.org/scripttemplates/202401.2.0/otBannerSdk.js | 104 KB | 55 KB (53%) | ✓ | 3rd |
| https://www.googletagmanager.com/gtag/js?id=DC-5095325&cx=c>m=4e64k0h1 | 131 KB | 55 KB (42%) | ✓ | 3rd |
| https://www.googletagmanager.com/gtag/js?id=AW-1014904604&cx=c>m=4e64k0h1 | 138 KB | 55 KB (40%) | ✓ | 3rd |
Consider code splitting or tree shaking to reduce unused code.
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.
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.
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.
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.
This bundle has high unused code — code-split or tree-shake to ship only what executes.
Source: web.dev / Lighthouse coverage
FPage Weight InventoryAction469 resources · 4.6 MB · 1.1 MB savings availableFIX
~1.1 MiB of savings available
| # | Resource | Type | Size | Cache | Unused | 3rd party | Issues |
|---|---|---|---|---|---|---|---|
| — | — | ||||||
| 469 resources | 4.6 MiB | ||||||
FHTTP CachingActionNo cache headersFIX
No Cache-Control header
Adding a Cache-Control header can significantly improve repeat-visit performance.
CImage OptimizationAction99 images, 0 KB saveableREVIEW
Set explicit width and height to prevent CLS.
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.
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.
Image without explicit width/height — browser can't reserve space; CLS jumps when image loads.
Source: web.dev / Core Web Vitals
CGreen HostingActionWhether the site is served from green-energy infrastructureREVIEW
Green Hosting
No green hosting detected
A+Text CompressionAll text resources are compressedPASS
A+Font Loading3 fonts (88 KB)PASS
Web fonts
3
88 KB total
Render-blocking
0
of 3
Dominant font-display
swap
Most common across fonts
Font loading timeline
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 CachingAll resources properly cachedPASS
A+Critical Rendering PathNo render-blocking resourcesPASS
A+Resource HintsNo optimization neededPASS
A+Render-Blocking ResourcesNo render-blocking resources detectedPASS
A+Third-Party ResourcesNo third-party resources detectedPASS
Network Waterfall469 requests over 10869msINFO
Third-Party Script CostPer-script blocking time, transfer cost, and cache headersINFO
| Script | Category | Execution | Transfer | Unused | Monthly Cost | Verdict |
|---|---|---|---|---|---|---|
www.cars.com www.cars.com | Other | 5694ms | 141 KB | — | $76/mo | Costly |
www.cars.com www.cars.com | Other | 4470ms | 144 KB | 43% | $59/mo | Costly |
Unattributable Unattributable | Other | 3166ms | 0 KB | — | $42/mo | Costly |
securepubads.g.doubleclick.net securepubads.g.doubleclick.net | Other | 2508ms | 188 KB | 47% | $33/mo | Costly |
www.cars.com www.cars.com | Other | 1154ms | 1 KB | 21% | $15/mo | Costly |
Google Tag Manager www.googletagmanager.com | Tag Manager | 758ms | 146 KB | 36% | $10/mo | Costly |
Google Tag Manager www.googletagmanager.com | Tag Manager | 748ms | 182 KB | 27% | $10/mo | Costly |
c.aaxads.com c.aaxads.com | Other | 748ms | 0 KB | — | $10/mo | Costly |
wsv3cdn.audioeye.com wsv3cdn.audioeye.com | Other | 739ms | 124 KB | 53% | $10/mo | Costly |
Microsoft Clarity scripts.clarity.ms | Session Replay | 739ms | 25 KB | — | $10/mo | Costly |
cdn.doubleverify.com cdn.doubleverify.com | Other | 710ms | 94 KB | 36% | $9/mo | Costly |
scripts.webcontentassessor.com scripts.webcontentassessor.com | Other | 539ms | 101 KB | — | $7/mo | Costly |
siteintercept.qualtrics.com siteintercept.qualtrics.com | Other | 532ms | 36 KB | 62% | $7/mo | Costly |
Google Tag Manager www.googletagmanager.com | Tag Manager | 502ms | 138 KB | 40% | $7/mo | Costly |
www.cars.com www.cars.com | Other | 496ms | 23 KB | — | $7/mo | Costly |
pagead2.googlesyndication.com pagead2.googlesyndication.com | Other | 487ms | 73 KB | 42% | $6/mo | Costly |
OneTrust cdn.cookielaw.org | Consent | 474ms | 104 KB | 53% | $6/mo | Essential |
Google Tag Manager www.googletagmanager.com | Tag Manager | 424ms | 131 KB | 42% | $6/mo | Costly |
www.cars.com www.cars.com | Other | 419ms | 34 KB | 66% | $6/mo | Costly |
wsv3cdn.audioeye.com wsv3cdn.audioeye.com | Other | 335ms | 14 KB | — | $4/mo | Costly |
Google Tag Manager www.googletagmanager.com | Tag Manager | 334ms | 161 KB | 40% | $4/mo | Costly |
www.cars.com www.cars.com | Other | 334ms | 86 KB | 47% | $4/mo | Costly |
www.cars.com www.cars.com | Other | 331ms | 9 KB | — | $4/mo | Costly |
ep2.adtrafficquality.google ep2.adtrafficquality.google | Other | 302ms | 8 KB | — | $4/mo | Costly |
sc-static.net sc-static.net | Other | 282ms | 25 KB | — | $4/mo | Costly |
analytics.tiktok.com analytics.tiktok.com | Other | 272ms | 106 KB | 57% | $4/mo | Costly |
Google Tag Manager www.googletagmanager.com | Tag Manager | 238ms | 130 KB | 47% | $3/mo | Costly |
www.cars.com www.cars.com | Other | 216ms | 2 KB | — | $3/mo | Costly |
static.criteo.net static.criteo.net | Other | 182ms | 25 KB | — | $2/mo | Optional |
Facebook Pixel connect.facebook.net | Advertising | 180ms | 97 KB | 38% | $2/mo | Optional |
tags-cdn.clarivoy.com tags-cdn.clarivoy.com | Other | 178ms | 26 KB | — | $2/mo | Optional |
www.cars.com www.cars.com | Other | 154ms | 5 KB | — | $2/mo | Optional |
www.cars.com www.cars.com | Other | 147ms | 2 KB | — | $2/mo | Optional |
Facebook Pixel connect.facebook.net | Advertising | 142ms | 46 KB | — | $2/mo | Optional |
static.criteo.net static.criteo.net | Other | 139ms | 15 KB | — | $2/mo | Optional |
www.cars.com www.cars.com | Other | 134ms | 2 KB | — | $2/mo | Optional |
accounts.google.com accounts.google.com | Other | 129ms | 96 KB | 71% | $2/mo | Optional |
sslwidget.criteo.com sslwidget.criteo.com | Other | 124ms | 4 KB | — | $2/mo | Optional |
tps.doubleverify.com tps.doubleverify.com | Other | 123ms | 1 KB | — | $2/mo | Optional |
cdn.doubleverify.com cdn.doubleverify.com | Other | 120ms | 4 KB | — | $2/mo | Optional |
launchpad.privacymanager.io launchpad.privacymanager.io | Other | 115ms | 41 KB | — | $2/mo | Optional |
Facebook Pixel connect.facebook.net | Advertising | 114ms | 18 KB | — | $2/mo | Optional |
analytics.tiktok.com analytics.tiktok.com | Other | 113ms | 40 KB | — | $2/mo | Optional |
securepubads.g.doubleclick.net securepubads.g.doubleclick.net | Other | 108ms | 34 KB | — | $1/mo | Optional |
OneTrust cdn.cookielaw.org | Consent | 105ms | 9 KB | — | $1/mo | Essential |
www.cars.com www.cars.com | Other | 98ms | 11 KB | — | $1/mo | Optional |
cdn.id5-sync.com cdn.id5-sync.com | Other | 88ms | 34 KB | — | $1/mo | Optional |
www.cars.com www.cars.com | Other | 88ms | 1 KB | — | $1/mo | Optional |
wsv3cdn.audioeye.com wsv3cdn.audioeye.com | Other | 84ms | 7 KB | — | $1/mo | Optional |
www.cars.com www.cars.com | Other | 77ms | 3 KB | — | $1/mo | Optional |
js.adsrvr.org js.adsrvr.org | Other | 63ms | 0 KB | — | $1/mo | Optional |
launchpad-wrapper.privacymanager.io launchpad-wrapper.privacymanager.io | Other | 61ms | 2 KB | — | $1/mo | Optional |
www.cars.com www.cars.com | Other | 57ms | 1 KB | — | $1/mo | Optional |
www.cars.com www.cars.com | Other | 55ms | 1 KB | — | $1/mo | Optional |
ats-wrapper.privacymanager.io ats-wrapper.privacymanager.io | Other | 54ms | 39 KB | 58% | $1/mo | Optional |
www.cars.com www.cars.com | Other | 53ms | 6 KB | — | $1/mo | Optional |
These scripts may cost more than they're worth
- www.cars.com adds 5694ms and costs ~$76/month
- www.cars.com adds 4470ms and costs ~$59/month
- Unattributable adds 3166ms and costs ~$42/month
- securepubads.g.doubleclick.net adds 2508ms and costs ~$33/month
- www.cars.com adds 1154ms and costs ~$15/month
- Google Tag Manager adds 758ms and costs ~$10/month
- Google Tag Manager adds 748ms and costs ~$10/month
- c.aaxads.com adds 748ms and costs ~$10/month
- wsv3cdn.audioeye.com adds 739ms and costs ~$10/month
- Microsoft Clarity adds 739ms and costs ~$10/month
- cdn.doubleverify.com adds 710ms and costs ~$9/month
- scripts.webcontentassessor.com adds 539ms and costs ~$7/month
- siteintercept.qualtrics.com adds 532ms and costs ~$7/month
- Google Tag Manager adds 502ms and costs ~$7/month
- www.cars.com adds 496ms and costs ~$7/month
- pagead2.googlesyndication.com adds 487ms and costs ~$6/month
- Google Tag Manager adds 424ms and costs ~$6/month
- www.cars.com adds 419ms and costs ~$6/month
- wsv3cdn.audioeye.com adds 335ms and costs ~$4/month
- Google Tag Manager adds 334ms and costs ~$4/month
- www.cars.com adds 334ms and costs ~$4/month
- www.cars.com adds 331ms and costs ~$4/month
- ep2.adtrafficquality.google adds 302ms and costs ~$4/month
- sc-static.net adds 282ms and costs ~$4/month
- analytics.tiktok.com adds 272ms and costs ~$4/month
- Google Tag Manager adds 238ms and costs ~$3/month
- www.cars.com adds 216ms and costs ~$3/month
100% of JavaScript execution time is spent on third-party scripts. Consider auditing which scripts are essential.
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.cars.com takes 5694ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
www.cars.com takes 4470ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
Unattributable takes 3166ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
securepubads.g.doubleclick.net takes 2508ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
www.cars.com takes 1154ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
Google Tag Manager takes 758ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
Google Tag Manager takes 748ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
c.aaxads.com takes 748ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
wsv3cdn.audioeye.com takes 739ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
53% of wsv3cdn.audioeye.com's code is unused. The script may be loading features you don't use.
Bundle has high unused-code ratio — tree-shaking and route-splitting recover the wasted bytes.
Source: web.dev
Microsoft Clarity takes 739ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
cdn.doubleverify.com takes 710ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
scripts.webcontentassessor.com takes 539ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
siteintercept.qualtrics.com takes 532ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
62% of siteintercept.qualtrics.com's code is unused. The script may be loading features you don't use.
Bundle has high unused-code ratio — tree-shaking and route-splitting recover the wasted bytes.
Source: web.dev
Google Tag Manager takes 502ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
www.cars.com takes 496ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
pagead2.googlesyndication.com takes 487ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
53% of OneTrust's code is unused. The script may be loading features you don't use.
Bundle has high unused-code ratio — tree-shaking and route-splitting recover the wasted bytes.
Source: web.dev
Google Tag Manager takes 424ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
www.cars.com takes 419ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
66% of www.cars.com's code is unused. The script may be loading features you don't use.
Bundle has high unused-code ratio — tree-shaking and route-splitting recover the wasted bytes.
Source: web.dev
wsv3cdn.audioeye.com takes 335ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
Google Tag Manager takes 334ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
www.cars.com takes 334ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
www.cars.com takes 331ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
ep2.adtrafficquality.google takes 302ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
sc-static.net takes 282ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
analytics.tiktok.com takes 272ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
57% of analytics.tiktok.com's code is unused. The script may be loading features you don't use.
Bundle has high unused-code ratio — tree-shaking and route-splitting recover the wasted bytes.
Source: web.dev
Google Tag Manager takes 238ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
www.cars.com takes 216ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
71% of accounts.google.com's code is unused. The script may be loading features you don't use.
Bundle has high unused-code ratio — tree-shaking and route-splitting recover the wasted bytes.
Source: web.dev
58% of ats-wrapper.privacymanager.io's code is unused. The script may be loading features you don't use.
Bundle has high unused-code ratio — tree-shaking and route-splitting recover the wasted bytes.
Source: web.dev