Skip to content
https://man7.org

Performance

· 14 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
96
GRADE
A
FIX
1
REVIEW
2
PASS
10
INFO
1

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

Mobile Desktop
100
Performance Overall performance score (0–100) based on Core Web Vitals and other metrics. 90+ is good.
96
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.

472 ms

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

803 ms

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.

0.007

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

472 ms

Time to Interactive Time to Interactive — how long until the page is fully interactive and responds to user input. Under 3.8s is good.

803 ms

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
14
10 PASS 2 REVIEW 1 FIX
D
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.
Info::
ETag present — enables conditional (304) responses
Info::
Last-Modified header present

No Cache-Control header

Adding a Cache-Control header can significantly improve repeat-visit performance.

B
Image Optimization
3 images, 0 KB saveable
REVIEW
3 images, 0 KB saveable
Warning::
https://man7.org/tlpi/cover/TLPI-front-cover-small... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://man7.org/photos/mtk_2021_200.jpg is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
3 images 112 KB
0 oversized -0 KB
3 legacy format
2 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

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

Green Hosting

No green hosting detected

A+
Page Weight Budget
166 KB transferred, 9 requests
PASS
166 KB transferred, 9 requests
Info::
Page weighs 229 KB (166 KB transferred)
Info::
9 HTTP requests
Info::
Estimated 0.03 g CO2 per page load
166 KB / 2.4 MB budget
166 KB transferred
9 requests
0.03 g CO2 per page load
Images 111.8 KiB 68%
JavaScript 34.9 KiB 21%
Other 15.1 KiB 9%
HTML 1.8 KiB 1%
CSS 1.4 KiB 1%
Other 511 B 0%
0 2.4 MB 4.9 MB
Under budget
A
Third-Party Impact
22% third-party, 0 ms blocking
PASS
22% third-party, 0 ms blocking
Info::
Third-party code accounts for 22% of page weight (35.8 KiB of 165.5 KiB)
Info::
Third-party blocking time is low (0 ms)
78%
22%
First-party Third-party
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+
JS Execution Cost
No JS execution data
PASS
No JS execution data
Info::
No significant JS execution detected

Main Thread Breakdown

Script Evaluation 49% Other 35% Style & Layout 9% Script Parsing & Compilation 4%
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
2 scripts, 0 KB unused
PASS
2 scripts, 0 KB unused
0 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://www.statcounter.com/counter/counter.js17 KB—✓3rd
https://ssl.google-analytics.com/ga.js17 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
No optimization needed
PASS
No optimization needed
Info::
No resource hint issues
A+
Page Weight Inventory
9 resources · 166 KB · 0 KB savings available
PASS
9 resources · 166 KB · 0 KB savings available
Info::
Within 1MB page-weight target
Got: 166 KB
Info::
4 third-party resources (22% of weight)
9 resources · 165.5 KiB · 4 third-party Within 1MB page-weight target
Image 77% · 126.9 KiB
JavaScript 21% · 34.9 KiB
Document 1% · 1.8 KiB
CSS 1% · 1.4 KiB
Other 0% · 511 B
Network Waterfall
9 requests over 404ms
INFO
0 ms 200 ms 400 ms 600 ms 800 ms FCP 472 ms LCP 803 mshttps://man7.org// https://man7.org/ — 200 — 1.8 KiB — 134 ms — http/1.1https://man7.org/style.css/style.css https://man7.org/style.css — 200 — 1.4 KiB — 46 ms — http/1.1https://man7.org/photos/mtk_2021_200.jpg/photos/mtk_2021_200.jpg https://man7.org/photos/mtk_2021_200.jpg — 200 — 47.3 KiB — 123 ms — http/1.1https://man7.org/tlpi/cover/TLPI-front-cover-small-256.png/tlpi/cover/TLPI-front-cover-small-... https://man7.org/tlpi/cover/TLPI-front-cover-small-256.png — 200 — 64.1 KiB — 168 ms — http/1.1https://www.statcounter.com/counter/counter.jswww.statcounter.com/counter/counter... https://www.statcounter.com/counter/counter.js — 200 — 17.5 KiB — 73 ms — h3https://ssl.google-analytics.com/ga.jsssl.google-analytics.com/ga.js https://ssl.google-analytics.com/ga.js — 200 — 17.4 KiB — 79 ms — h2https://c.statcounter.com/t.php?sc_project=6129341&u1=A3DAE1F1451D4095B6FD722D2D9B8BBE&java=1&security=1192a2fb&sc_snum=1&sess=609793&p=0&pv=10.15&rcat=d&rdom=d&rdomg=new&bb=1&jg=new&rr=1.1.1.1.1.1.1.1.1&sc_bot=0&resolution=800&h=600&camefrom=&u=https%3A//man7.org/&t=Michael%20Kerrisk%20-%20man7.org&invisible=1&sc_rum_e_s=227&sc_rum_e_e=253&sc_rum_f_s=0&sc_rum_f_e=222&get_config=truec.statcounter.com/t.php?sc_project=... https://c.statcounter.com/t.php?sc_project=6129341&u1=A3DAE1F1451D4095B6FD722D2D9B8BBE&java=1&security=1192a2fb&sc_snum=1&sess=609793&p=0&pv=10.15&rcat=d&rdom=d&rdomg=new&bb=1&jg=new&rr=1.1.1.1.1.1.1.1.1&sc_bot=0&resolution=800&h=600&camefrom=&u=https%3A//man7.org/&t=Michael%20Kerrisk%20-%20man7.org&invisible=1&sc_rum_e_s=227&sc_rum_e_e=253&sc_rum_f_s=0&sc_rum_f_e=222&get_config=true — 200 — 511 B — 153 ms — h3https://ssl.google-analytics.com/r/__utm.gif?utmwv=5.7.2&utms=1&utmn=978844338&utmhn=man7.org&utmcs=UTF-8&utmsr=800x600&utmvp=1350x940&utmsc=24-bit&utmul=en-us&utmje=0&utmfl=-&utmdt=Michael%20Kerrisk%20-%20man7.org&utmhid=1538605627&utmr=-&utmp=%2F&utmht=1776800840253&utmac=UA-9830363-2&utmcc=__utma%3D141474094.25420735.1776800840.1776800840.1776800840.1%3B%2B__utmz%3D141474094.1776800840.1.1.utmcsr%3D(direct)%7Cutmccn%3D(direct)%7Cutmcmd%3D(none)%3B&utmjid=284106120&utmredir=1&utmu=qAAAAAAAAAAAAAAAAAAAAAAE~ssl.google-analytics.com/r/__utm.gi... https://ssl.google-analytics.com/r/__utm.gif?utmwv=5.7.2&utms=1&utmn=978844338&utmhn=man7.org&utmcs=UTF-8&utmsr=800x600&utmvp=1350x940&utmsc=24-bit&utmul=en-us&utmje=0&utmfl=-&utmdt=Michael%20Kerrisk%20-%20man7.org&utmhid=1538605627&utmr=-&utmp=%2F&utmht=1776800840253&utmac=UA-9830363-2&utmcc=__utma%3D141474094.25420735.1776800840.1776800840.1776800840.1%3B%2B__utmz%3D141474094.1776800840.1.1.utmcsr%3D(direct)%7Cutmccn%3D(direct)%7Cutmcmd%3D(none)%3B&utmjid=284106120&utmredir=1&utmu=qAAAAAAAAAAAAAAAAAAAAAAE~ — 200 — 440 B — 26 ms — h2https://man7.org/koru-icon.png/koru-icon.png https://man7.org/koru-icon.png — 200 — 15.1 KiB — 45 ms — http/1.1
HTML JavaScript CSS Images Fonts XHR/Fetch Other
All checks on this page are automated. Results are estimates - run targeted manual reviews when the score affects a release decision.

Send Feedback