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https://irfanview.com

Performance

· 17 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
91
GRADE
A
FIX
2
REVIEW
2
PASS
11
INFO
2

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

Mobile Desktop
82
Performance Overall performance score (0–100) based on Core Web Vitals and other metrics. 90+ is good.
82
Accessibility Measures how accessible the page is for users with disabilities. Checks color contrast, ARIA labels, and semantic HTML.
96
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.

2.01 s

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

2.76 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.

0.238

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

2.01 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.

2.76 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
11 PASS 2 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 (163.4 KiB of 163.5 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.

C
Image Optimization
Action
9 images, 0 KB saveable
REVIEW
9 images, 0 KB saveable
Warning::
https://www.irfanview.com/images/logo-download.png is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.irfanview.com/images/banner_daisy.jpg is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.irfanview.com/images/logo-footer.png is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.irfanview.com/images/logo.png is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.irfanview.com/images/profile-pic.gif is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
9 images 151 KB
0 oversized -0 KB
9 legacy format
5 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

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

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
164 KB transferred, 13 requests
PASS
164 KB transferred, 13 requests
Info::
Page weighs 207 KB (164 KB transferred)
Info::
13 HTTP requests
Info::
Estimated 0.03 g CO2 per page load
164 KB / 2.4 MB budget
164 KB transferred
13 requests
0.03 g CO2 per page load
Images 151.5 KiB 93%
CSS 6.7 KiB 4%
Other 2.9 KiB 2%
HTML 2.5 KiB 2%
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+
JS Execution Cost
273ms total JS execution
PASS
273ms total JS execution
Info::
https://www.irfanview.com/: 147ms CPU time
Info::
Unattributable: 126ms CPU time
Warning::
Third-party scripts: 273ms (100% of total)

Main Thread Breakdown

Other 51% Style & Layout 35% Rendering 6% Script Evaluation 4% Parse HTML & CSS 3%
ScriptTotalScriptingParse/CompileParty
https://www.irfanview.com/147ms5ms1ms3rd
Unattributable126ms6ms0ms3rd
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
No JavaScript
PASS
No JavaScript
Info::
No JavaScript bundles
No JavaScript files loaded.
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
13 resources · 164 KB · 0 KB savings available
PASS
13 resources · 164 KB · 0 KB savings available
Info::
Within 1MB page-weight target
Got: 164 KB
Warning::
12 third-party resources (100% of weight)
13 resources · 163.5 KiB · 12 third-party Within 1MB page-weight target
Image 94% · 154.3 KiB
CSS 4% · 6.7 KiB
Document 2% · 2.6 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
Network Waterfall
13 requests over 762ms
INFO
0 ms 500 ms 1.0 s 1.5 s 2.0 s 2.5 s FCP 2.0 s LCP 2.8 shttps://irfanview.com// https://irfanview.com/ — 301 — 99 B — 278 ms — h2https://www.irfanview.com/www.irfanview.com/ https://www.irfanview.com/ — 200 — 2.5 KiB — 101 ms — h2https://www.irfanview.com/style.csswww.irfanview.com/style.css https://www.irfanview.com/style.css — 200 — 6.7 KiB — 102 ms — h2https://www.irfanview.com/images/logo.pngwww.irfanview.com/images/logo.png https://www.irfanview.com/images/logo.png — 200 — 6.3 KiB — 99 ms — h2https://www.irfanview.com/images/banner_daisy.jpgwww.irfanview.com/images/banner_dai... https://www.irfanview.com/images/banner_daisy.jpg — 200 — 90.2 KiB — 195 ms — h2https://www.irfanview.com/images/profile-pic.gifwww.irfanview.com/images/profile-pi... https://www.irfanview.com/images/profile-pic.gif — 200 — 3.8 KiB — 105 ms — h2https://www.irfanview.com/images/logo-download.pngwww.irfanview.com/images/logo-downl... https://www.irfanview.com/images/logo-download.png — 200 — 6.2 KiB — 101 ms — h2https://www.irfanview.com/images/logo-footer.pngwww.irfanview.com/images/logo-foote... https://www.irfanview.com/images/logo-footer.png — 200 — 5.2 KiB — 98 ms — h2https://www.irfanview.com/images/banner-bg.jpgwww.irfanview.com/images/banner-bg.... https://www.irfanview.com/images/banner-bg.jpg — 200 — 35.7 KiB — 160 ms — h2https://www.irfanview.com/images/bullet2.pngwww.irfanview.com/images/bullet2.pn... https://www.irfanview.com/images/bullet2.png — 200 — 1.2 KiB — 95 ms — h2https://www.irfanview.com/images/download-icon-white.pngwww.irfanview.com/images/download-i... https://www.irfanview.com/images/download-icon-white.png — 200 — 1.4 KiB — 160 ms — h2https://www.irfanview.com/images/download-icon-black.pngwww.irfanview.com/images/download-i... https://www.irfanview.com/images/download-icon-black.png — 200 — 1.5 KiB — 95 ms — h2https://www.irfanview.com/images/favicon.pngwww.irfanview.com/images/favicon.pn... https://www.irfanview.com/images/favicon.png — 200 — 2.8 KiB — 95 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 273ms · 2KB · €3/mo
www.irfanview.com
Other
Optional
Execution 147ms
Transfer 2 KB
Monthly Cost €2/mo
Unattributable
Other
Optional
Execution 126ms
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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