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https://bookstime.com

Performance

· 17 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
95
GRADE
A
FIX
2
REVIEW
0
PASS
13
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.
88
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.
92
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.

1.73 s

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

2.16 s

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

0 ms

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

0.079

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

1.73 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.

2.17 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
17
13 PASS 2 FIX
D
Third-Party Impact
Action
99% third-party, 0 ms blocking
FIX
99% third-party, 0 ms blocking
Warning::
Third-party code accounts for 99% of page weight (83.0 KiB of 83.5 KiB)
Info::
Third-party blocking time is low (0 ms)
99%
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.

A+
Page Weight Budget
83 KB transferred, 16 requests
PASS
83 KB transferred, 16 requests
Info::
Page weighs 179 KB (83 KB transferred)
Info::
16 HTTP requests
Info::
Estimated 0.02 g CO2 per page load
83 KB / 2.4 MB budget
83 KB transferred
16 requests
0.02 g CO2 per page load
Images 51.1 KiB 61%
HTML 15.1 KiB 18%
CSS 9.3 KiB 11%
JavaScript 7.6 KiB 9%
Other 451 B 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
8 images, 0 KB saveable
PASS
8 images, 0 KB saveable
Info::
All images are well-optimized
8 images 51 KB
0 oversized -0 KB
0 legacy format
0 missing dimensions CLS risk
A+
JS Execution Cost
250ms total JS execution
PASS
250ms total JS execution
Info::
https://www.bookstime.com/: 158ms CPU time
Info::
Unattributable: 92ms CPU time
Warning::
Third-party scripts: 250ms (100% of total)

Main Thread Breakdown

Other 38% Style & Layout 33% Script Evaluation 15% Parse HTML & CSS 7% Rendering 6%
ScriptTotalScriptingParse/CompileParty
https://www.bookstime.com/158ms24ms4ms3rd
Unattributable92ms6ms0ms3rd
A+
Font Loading
No web fonts (system fonts)
PASS
No web fonts (system fonts)
Info::
No web fonts loaded — system fonts are fastest
No web fonts loaded — system fonts are optimal.
A+
JS Bundles
5 scripts, 0 KB unused
PASS
5 scripts, 0 KB unused
0 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://www.bookstime.com/wp-content/cache/autoptimize/js/autoptimize_single_d15948c46caba0e98253d8e6d58a1e75.js?ver=6.4.21 KB—✓3rd
https://www.bookstime.com/wp-content/cache/autoptimize/js/autoptimize_single_00c9129b65c6d7b004242d021002c77c.js1 KB—✓3rd
https://www.bookstime.com/wp-content/cache/autoptimize/js/autoptimize_single_a62e653adc2ad2b15286e740014219db.js1 KB—✓3rd
https://www.bookstime.com/wp-content/cache/autoptimize/js/autoptimize_single_43701318bd1d5cd797d720412647dc0f.js?ver=2.2.51 KB—✓3rd
https://www.bookstime.com/wp-content/plugins/rocket-lazy-load/assets/js/16.1/lazyload.min.js3 KB—✓3rd
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
2 hints, 0 missing preconnects
PASS
2 hints, 0 missing preconnects
Info::
Page uses 2 resource hint(s)

Current Resource Hints

preconnect
—
preload
2
dns-prefetch
—
prefetch
—

2 resource hints configured

A
Page Weight Inventory
16 resources · 83 KB · 0 KB savings available
PASS
16 resources · 83 KB · 0 KB savings available
Info::
Within 1MB page-weight target
Got: 83 KB
Warning::
15 third-party resources (99% of weight)
16 resources · 83.5 KiB · 15 third-party Within 1MB page-weight target
Image 61% · 51.1 KiB
Document 19% · 15.5 KiB
CSS 11% · 9.3 KiB
JavaScript 9% · 7.6 KiB
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
A+
Green Hosting
Whether the site is served from green-energy infrastructure
PASS

Green Hosting

This site is hosted on green energy infrastructure

Provider: Cloudflare

Network Waterfall
16 requests over 232ms
INFO
0 ms 500 ms 1.0 s 1.5 s 2.0 s FCP 1.7 s LCP 2.2 shttps://bookstime.com// https://bookstime.com/ — 301 — 451 B — 109 ms — h2https://www.bookstime.com/www.bookstime.com/ https://www.bookstime.com/ — 200 — 15.1 KiB — 62 ms — h2https://www.bookstime.com/wp-content/cache/autoptimize/css/autoptimize_03274234cf0de591797752ca2c2eefe8.csswww.bookstime.com/wp-content/cache/... https://www.bookstime.com/wp-content/cache/autoptimize/css/autoptimize_03274234cf0de591797752ca2c2eefe8.css — 200 — 9.3 KiB — 31 ms — h2https://www.bookstime.com/wp-content/uploads/2024/02/new-header-bg-mob.webpwww.bookstime.com/wp-content/upload... https://www.bookstime.com/wp-content/uploads/2024/02/new-header-bg-mob.webp — 200 — 16.8 KiB — 32 ms — h2https://www.bookstime.com/wp-content/uploads/2024/01/new-header-bg-1024x410.webpwww.bookstime.com/wp-content/upload... https://www.bookstime.com/wp-content/uploads/2024/01/new-header-bg-1024x410.webp — 200 — 34.3 KiB — 42 ms — h2https://www.bookstime.com/wp-content/cache/autoptimize/js/autoptimize_single_d15948c46caba0e98253d8e6d58a1e75.js?ver=6.4.2www.bookstime.com/wp-content/cache/... https://www.bookstime.com/wp-content/cache/autoptimize/js/autoptimize_single_d15948c46caba0e98253d8e6d58a1e75.js?ver=6.4.2 — 200 — 776 B — 22 ms — h2https://www.bookstime.com/wp-content/cache/autoptimize/js/autoptimize_single_00c9129b65c6d7b004242d021002c77c.jswww.bookstime.com/wp-content/cache/... https://www.bookstime.com/wp-content/cache/autoptimize/js/autoptimize_single_00c9129b65c6d7b004242d021002c77c.js — 200 — 1.5 KiB — 21 ms — h2https://www.bookstime.com/wp-content/cache/autoptimize/js/autoptimize_single_a62e653adc2ad2b15286e740014219db.jswww.bookstime.com/wp-content/cache/... https://www.bookstime.com/wp-content/cache/autoptimize/js/autoptimize_single_a62e653adc2ad2b15286e740014219db.js — 200 — 1.1 KiB — 24 ms — h2https://www.bookstime.com/wp-content/cache/autoptimize/js/autoptimize_single_43701318bd1d5cd797d720412647dc0f.js?ver=2.2.5www.bookstime.com/wp-content/cache/... https://www.bookstime.com/wp-content/cache/autoptimize/js/autoptimize_single_43701318bd1d5cd797d720412647dc0f.js?ver=2.2.5 — 200 — 1.0 KiB — 25 ms — h2data:image/webp;base64,UklGRjAEAABXRUJQVlA4TCQEAAAvpgAGEK/CqG0kSZ7zPVCG6RDe7aLhoG0kSXL1vjCW2fHncDPl…data:image/webp;base64,UklGRjAEAABX... data:image/webp;base64,UklGRjAEAABXRUJQVlA4TCQEAAAvpgAGEK/CqG0kSZ7zPVCG6RDe7aLhoG0kSXL1vjCW2fHncDPl… — 200 — 0 B — 0 ms — datahttps://www.bookstime.com/wp-content/plugins/rocket-lazy-load/assets/js/16.1/lazyload.min.jswww.bookstime.com/wp-content/plugin... https://www.bookstime.com/wp-content/plugins/rocket-lazy-load/assets/js/16.1/lazyload.min.js — 200 — 3.2 KiB — 26 ms — h2data:image/svg+xml,%3Csvg%20xmlns='http://www.w3.org/2000/svg'%20viewBox='0%200%20640%20568'%3E%3C/…www.w3.org/2000/svg'%20viewBox='0%2... data:image/svg+xml,%3Csvg%20xmlns='http://www.w3.org/2000/svg'%20viewBox='0%200%20640%20568'%3E%3C/… — 200 — 0 B — 0 ms — datadata:image/svg+xml,%3Csvg%20xmlns='http://www.w3.org/2000/svg'%20viewBox='0%200%20640%20569'%3E%3C/…www.w3.org/2000/svg'%20viewBox='0%2... data:image/svg+xml,%3Csvg%20xmlns='http://www.w3.org/2000/svg'%20viewBox='0%200%20640%20569'%3E%3C/… — 200 — 0 B — 0 ms — datadata:image/svg+xml,%3Csvg%20xmlns='http://www.w3.org/2000/svg'%20viewBox='0%200%2010%2010'%3E%3C/sv…www.w3.org/2000/svg'%20viewBox='0%2... data:image/svg+xml,%3Csvg%20xmlns='http://www.w3.org/2000/svg'%20viewBox='0%200%2010%2010'%3E%3C/sv… — 200 — 0 B — 0 ms — datadata:image/svg+xml,%3Csvg%20xmlns='http://www.w3.org/2000/svg'%20viewBox='0%200%20100%2020'%3E%3C/s…www.w3.org/2000/svg'%20viewBox='0%2... data:image/svg+xml,%3Csvg%20xmlns='http://www.w3.org/2000/svg'%20viewBox='0%200%20100%2020'%3E%3C/s… — 200 — 0 B — 0 ms — datadata:image/svg+xml,%3Csvg%20xmlns='http://www.w3.org/2000/svg'%20viewBox='0%200%2030%2030'%3E%3C/sv…www.w3.org/2000/svg'%20viewBox='0%2... data:image/svg+xml,%3Csvg%20xmlns='http://www.w3.org/2000/svg'%20viewBox='0%200%2030%2030'%3E%3C/sv… — 200 — 0 B — 0 ms — data
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 250ms · 15KB · $1/mo
www.bookstime.com
Other
Optional
Execution 158ms
Transfer 15 KB
Monthly Cost $1/mo
Unattributable
Other
Optional
Execution 92ms
Transfer 0 KB
Monthly Cost $1/mo

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

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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