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Performance

· 15 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
71
GRADE
C
FIX
4
REVIEW
4
PASS
5
INFO
2

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

Mobile Desktop
80
Performance Overall performance score (0–100) based on Core Web Vitals and other metrics. 90+ is good.
83
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.
75
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.

808 ms

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

2.86 s

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

68 ms

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

0.110

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

949 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.

2.86 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
5 PASS 4 REVIEW 4 FIX
F
Page Weight Budget
Action
16.2 MB transferred, 72 requests
FIX
16.2 MB transferred, 72 requests
Critical::
Page weighs 20.6 MB (16.2 MB transferred)
Warning::
Images are 14.2 MB — compress or use modern formats
Convert images to WebP/AVIF and resize to display dimensions to reduce transfer size.
Got: 14.2 MB
Warning::
JavaScript is 1.4 MB — consider code splitting or lazy loading
Large JavaScript bundles delay interactivity. Split code by route or defer non-critical scripts.
Got: 1.4 MB
Info::
72 HTTP requests
Info::
Estimated 3.4 g CO2 per page load
16.2 MB / 2.4 MB budget
16.2 MB transferred
72 requests
3.4 g CO2 per page load
Images 14.2 MiB 88%
JavaScript 1.4 MiB 9%
Other 250.4 KiB 2%
CSS 156.9 KiB 1%
HTML 75.9 KiB 0%
Fonts 44.1 KiB 0%
Other 553 B 0%
Other 546 B 0%
Other 546 B 0%
Other 0 B 0%
0 2.4 MB 4.9 MB
Over budget

Convert images to WebP/AVIF and resize to display dimensions to reduce transfer size.

Why this matters

Image bandwidth is high — modern formats (WebP/AVIF) and resizing typically cut it 50%+.

Source: web.dev

Large JavaScript bundles delay interactivity. Split code by route or defer non-critical scripts.

Why this matters

JavaScript bundle is large — code-split routes and lazy-load off-screen components to defer.

Source: web.dev

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 (16.2 MiB of 16.2 MiB)
Info::
Third-party blocking time is low (0 ms)
100%
First-party Third-party
D
Page Weight Inventory
Action
72 resources · 16.2 MB · 268 KB savings available
FIX
72 resources · 16.2 MB · 268 KB savings available
Warning::
Page weight 15.2 MB over 1MB target
Got: 16.2 MB Expected: ≤ 1 MB
Info::
~268 KB of savings available
Warning::
71 third-party resources (100% of weight)
Info::
20 resources over 200KB
72 resources · 16.2 MiB · 71 third-party 15.2 MiB over 1MB target
Image 89% · 14.5 MiB
JavaScript 9% · 1.4 MiB
CSS 1% · 156.9 KiB
Document 0% · 78.1 KiB
Font 0% · 44.1 KiB
Other 0% · 1.6 KiB

~267.9 KiB of savings available

Remove unused JavaScript: 267.9 KiB
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
32 images, 0 KB saveable
REVIEW
32 images, 0 KB saveable
Warning::
https://www.imo.org/Content/images/img/English_Whi... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.imo.org/Content/images/img/English_Col... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
32 images 14.2 MB
0 oversized -0 KB
28 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
JS Execution Cost
Action
1409ms total JS execution
REVIEW
1409ms total JS execution
Warning::
Unattributable: 532ms CPU time
Warning::
https://www.imo.org/: 359ms CPU time
Info::
https://www.imo.org/Scripts/js/vendors.js: 242ms CPU time
Info::
https://www.googletagmanager.com/gtag/js?id=UA-465...: 130ms CPU time
Info::
https://www.googletagmanager.com/gtag/js?id=G-JG4E...: 83ms CPU time
Warning::
Third-party scripts: 1409ms (100% of total)

Main Thread Breakdown

Other 38% Script Evaluation 32% Style & Layout 16% Script Parsing & Compilation 7% Rendering 4%
ScriptTotalScriptingParse/CompileParty
Unattributable532ms47ms0ms3rd
https://www.imo.org/359ms14ms20ms3rd
https://www.imo.org/Scripts/js/vendors.js242ms126ms14ms3rd
https://www.googletagmanager.com/gtag/js?id=UA-465405-9130ms107ms18ms3rd
https://www.googletagmanager.com/gtag/js?id=G-JG4ETTWXS1&cx=c&gtm=4e64k083ms63ms18ms3rd
https://maps.googleapis.com/maps/api/js?key=AIzaSyCDYY_ECpWhLm56VGe6abMJ8Msj_Nt_8LM62ms43ms17ms3rd
C
JS Bundles
Action
16 scripts, 268 KB unused
REVIEW
16 scripts, 268 KB unused
Warning::
https://maps.googleapis.com/maps/api/js?key=AIzaSy...: 65 KB unused (65%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.googletagmanager.com/gtag/js?id=UA-465...: 64 KB unused (51%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.googletagmanager.com/gtag/js?id=G-JG4E...: 63 KB unused (43%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://connect.facebook.net/en_GB/bundle/sdk.js/: 54 KB unused (70%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://ajax.googleapis.com/ajax/libs/jquery/3.4.1...: 22 KB unused (74%)
Consider code splitting or tree shaking to reduce unused code.
Info::
Total unused JavaScript: 268 KB
268 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://maps.googleapis.com/maps/api/js?key=AIzaSyCDYY_ECpWhLm56VGe6abMJ8Msj_Nt_8LM100 KB65 KB (65%)✓3rd
https://www.googletagmanager.com/gtag/js?id=UA-465405-9125 KB64 KB (51%)✓3rd
https://www.googletagmanager.com/gtag/js?id=G-JG4ETTWXS1&cx=c&gtm=4e64k0146 KB63 KB (43%)✓3rd
https://connect.facebook.net/en_GB/bundle/sdk.js/78 KB54 KB (70%)✓3rd
https://ajax.googleapis.com/ajax/libs/jquery/3.4.1/jquery.min.js31 KB22 KB (74%)✓3rd
https://www.youtube.com/s/player/1bb6ee63/player_embed_es6.vflset/en_US/base.js436 KB—✓3rd
https://www.imo.org/scripts/js/theme.js3 KB—✓3rd
https://www.imo.org/scripts/js/fbshare.js1 KB—✓3rd
https://www.imo.org/scripts/js/d3.js73 KB—✓3rd
https://www.imo.org/scripts/js/vendors.js106 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

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

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

Green Hosting

No green hosting detected

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+
Font Loading
2 fonts (44 KB)
PASS
2 fonts (44 KB)
Info::
2 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

2

44 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 1.5 s 2.0 s 2.5 s FCP 808 ms LCP 2.9 shttps://fonts.gstatic.com/s/roboto/v48/KFO7CnqEu92Fr1ME7kSn66aGLdTylUAMa3yUBHMdazQ.woff2KFO7CnqEu92Fr1ME7kSn66a... https://fonts.gstatic.com/s/roboto/v48/KFO7CnqEu92Fr1ME7kSn66aGLdTylUAMa3yUBHMdazQ.woff2 — 33.9 KiB — 47 ms — font-display: swaphttps://www.imo.org/content/css/fonts/theme-icons.ttf?wu7wi2theme-icons.ttf https://www.imo.org/content/css/fonts/theme-icons.ttf?wu7wi2 — 10.2 KiB — 40 ms — font-display: swap
KFO7CnqEu92Fr1ME7kSn66a... woff2 swap
Size 34 KB
Load time 47 ms
Start 458 ms
Risk FOUT — text flashes from fallback to web font
theme-icons.ttf ttf swap
Size 10 KB
Load time 40 ms
Start 515 ms
Risk FOUT — text flashes from fallback to web font
  • Convert to woff2 for ~30% smaller file size
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)

Fixing the unchecked items could save ~3 KB and ~6 ms

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
72 requests over 4307ms
INFO
0 ms 1.0 s 2.0 s 3.0 s 4.0 s FCP 808 ms LCP 2.9 shttps://imo.org// https://imo.org/ — 302 — 99 B — 30 ms — h2https://www.imo.org/www.imo.org/ https://www.imo.org/ — 200 — 18.0 KiB — 89 ms — h2https://ajax.googleapis.com/ajax/libs/jquery/3.4.1/jquery.min.jsajax.googleapis.com/ajax/libs/jquer... https://ajax.googleapis.com/ajax/libs/jquery/3.4.1/jquery.min.js — 200 — 30.7 KiB — 22 ms — h2https://www.googletagmanager.com/gtag/js?id=UA-465405-9www.googletagmanager.com/gtag/js?id... https://www.googletagmanager.com/gtag/js?id=UA-465405-9 — 200 — 125.3 KiB — 41 ms — h2https://www.imo.org/Content/css/css/main.css?v=1.2www.imo.org/Content/css/css/main.cs... https://www.imo.org/Content/css/css/main.css?v=1.2 — 301 — 241 B — 26 ms — h2https://www.imo.org/Content/images/img/English_Colour_RGB_Horizontal.pngwww.imo.org/Content/images/img/Engl... https://www.imo.org/Content/images/img/English_Colour_RGB_Horizontal.png — 301 — 257 B — 26 ms — h2https://wwwcdn.imo.org/localresources/en/MediaCentre/WhatsNew/PublishingImages/LEG%20113%20PB_banner%20medium.jpgwwwcdn.imo.org/localresources/en/Me... https://wwwcdn.imo.org/localresources/en/MediaCentre/WhatsNew/PublishingImages/LEG%20113%20PB_banner%20medium.jpg — 200 — 976.6 KiB — 226 ms — h2https://www.imo.org/content/css/css/main.css?v=1.2www.imo.org/content/css/css/main.cs... https://www.imo.org/content/css/css/main.css?v=1.2 — 200 — 53.6 KiB — 38 ms — h2https://www.imo.org/content/images/img/english_colour_rgb_horizontal.pngwww.imo.org/content/images/img/engl... https://www.imo.org/content/images/img/english_colour_rgb_horizontal.png — 200 — 86.5 KiB — 34 ms — h2https://wwwcdn.imo.org/localresources/en/MediaCentre/PublishingImages/HNS%20PB%20Banner_A_medium.jpgwwwcdn.imo.org/localresources/en/Me... https://wwwcdn.imo.org/localresources/en/MediaCentre/PublishingImages/HNS%20PB%20Banner_A_medium.jpg — 200 — 1.7 MiB — 554 ms — h2https://wwwcdn.imo.org/localresources/en/MediaCentre/WhatsNew/PublishingImages/SG%20Statement_medium__%201.jpgwwwcdn.imo.org/localresources/en/Me... https://wwwcdn.imo.org/localresources/en/MediaCentre/WhatsNew/PublishingImages/SG%20Statement_medium__%201.jpg — 200 — 1.3 MiB — 750 ms — h2https://wwwcdn.imo.org/localresources/en/MediaCentre/WhatsNew/PublishingImages/FALConclusion.jpgwwwcdn.imo.org/localresources/en/Me... https://wwwcdn.imo.org/localresources/en/MediaCentre/WhatsNew/PublishingImages/FALConclusion.jpg — 200 — 447.9 KiB — 542 ms — h2https://www.imo.org/Scripts/js/vendors.jswww.imo.org/Scripts/js/vendors.js https://www.imo.org/Scripts/js/vendors.js — 301 — 235 B — 247 ms — h2https://www.imo.org/Scripts/js/theme.jswww.imo.org/Scripts/js/theme.js https://www.imo.org/Scripts/js/theme.js — 301 — 232 B — 247 ms — h2https://maps.googleapis.com/maps/api/js?key=AIzaSyCDYY_ECpWhLm56VGe6abMJ8Msj_Nt_8LMmaps.googleapis.com/maps/api/js?key... https://maps.googleapis.com/maps/api/js?key=AIzaSyCDYY_ECpWhLm56VGe6abMJ8Msj_Nt_8LM — 200 — 100.4 KiB — 113 ms — h2https://www.imo.org/Scripts/js/fbShare.jswww.imo.org/Scripts/js/fbShare.js https://www.imo.org/Scripts/js/fbShare.js — 301 — 236 B — 246 ms — h2https://www.imo.org/Scripts/js/d3.jswww.imo.org/Scripts/js/d3.js https://www.imo.org/Scripts/js/d3.js — 301 — 232 B — 247 ms — h2https://wwwcdn.imo.org/localresources/en/MediaCentre/WhatsNew/PublishingImages/Applications%20Now%20Open_GV_medium.jpgwwwcdn.imo.org/localresources/en/Me... https://wwwcdn.imo.org/localresources/en/MediaCentre/WhatsNew/PublishingImages/Applications%20Now%20Open_GV_medium.jpg — 200 — 1.3 MiB — 768 ms — h2https://wwwcdn.imo.org/localresources/en/MediaCentre/WhatsNew/PublishingImages/Comoros%20launches%20National%20Maritime%20Security%20Committee%20with%20IMO%20support_medium.jpgwwwcdn.imo.org/localresources/en/Me... https://wwwcdn.imo.org/localresources/en/MediaCentre/WhatsNew/PublishingImages/Comoros%20launches%20National%20Maritime%20Security%20Committee%20with%20IMO%20support_medium.jpg — 200 — 1.1 MiB — 703 ms — h2https://wwwcdn.imo.org/localresources/en/MediaCentre/PublishingImages/Vessel%20Image%2002.jpgwwwcdn.imo.org/localresources/en/Me... https://wwwcdn.imo.org/localresources/en/MediaCentre/PublishingImages/Vessel%20Image%2002.jpg — 200 — 2.8 MiB — 827 ms — h2https://wwwcdn.imo.org/localresources/en/MediaCentre/PublishingImages/Middle%20East%20Hot%20Topic%20thumbnail.jpgwwwcdn.imo.org/localresources/en/Me... https://wwwcdn.imo.org/localresources/en/MediaCentre/PublishingImages/Middle%20East%20Hot%20Topic%20thumbnail.jpg — 200 — 251.8 KiB — 148 ms — h2https://wwwcdn.imo.org/localresources/en/MediaCentre/PublishingImages/WMD%202026%20event%20page%20thumbnail.jpgwwwcdn.imo.org/localresources/en/Me... https://wwwcdn.imo.org/localresources/en/MediaCentre/PublishingImages/WMD%202026%20event%20page%20thumbnail.jpg — 200 — 651.6 KiB — 655 ms — h2https://wwwcdn.imo.org/localresources/en/MediaCentre/HotTopics/PublishingImages/SeafarersInformationThumbnail.jpgwwwcdn.imo.org/localresources/en/Me... https://wwwcdn.imo.org/localresources/en/MediaCentre/HotTopics/PublishingImages/SeafarersInformationThumbnail.jpg — 200 — 184.2 KiB — 443 ms — h2https://wwwcdn.imo.org/localresources/en/MediaCentre/PublishingImages/MEPC%20meeting%20thumbnail_EN.jpgwwwcdn.imo.org/localresources/en/Me... https://wwwcdn.imo.org/localresources/en/MediaCentre/PublishingImages/MEPC%20meeting%20thumbnail_EN.jpg — 200 — 615.0 KiB — 636 ms — h2https://wwwcdn.imo.org/localresources/en/PublishingImages/our%20work.jpgwwwcdn.imo.org/localresources/en/Pu... https://wwwcdn.imo.org/localresources/en/PublishingImages/our%20work.jpg — 200 — 509.4 KiB — 527 ms — h2https://wwwcdn.imo.org/localresources/en/PublishingImages/entry-bg1.jpgwwwcdn.imo.org/localresources/en/Pu... https://wwwcdn.imo.org/localresources/en/PublishingImages/entry-bg1.jpg — 200 — 59.0 KiB — 173 ms — h2https://wwwcdn.imo.org/localresources/en/PublishingImages/maritime%20safety.jpgwwwcdn.imo.org/localresources/en/Pu... https://wwwcdn.imo.org/localresources/en/PublishingImages/maritime%20safety.jpg — 200 — 351.1 KiB — 495 ms — h2https://wwwcdn.imo.org/localresources/en/PublishingImages/IMO%20plenary_medium.jpgwwwcdn.imo.org/localresources/en/Pu... https://wwwcdn.imo.org/localresources/en/PublishingImages/IMO%20plenary_medium.jpg — 200 — 488.1 KiB — 636 ms — h2https://wwwcdn.imo.org/localresources/en/PublishingImages/entry-bg3.jpgwwwcdn.imo.org/localresources/en/Pu... https://wwwcdn.imo.org/localresources/en/PublishingImages/entry-bg3.jpg — 200 — 13.2 KiB — 107 ms — h2https://wwwcdn.imo.org/localresources/en/MediaCentre/PublishingImages/OurOceanBackground.jpgwwwcdn.imo.org/localresources/en/Me... https://wwwcdn.imo.org/localresources/en/MediaCentre/PublishingImages/OurOceanBackground.jpg — 200 — 274.5 KiB — 512 ms — h2
0 ms 1.0 s 2.0 s 3.0 s 4.0 s FCP 808 ms LCP 2.9 shttps://imo.org// https://imo.org/ — 302 — 99 B — 30 ms — h2https://www.imo.org/www.imo.org/ https://www.imo.org/ — 200 — 18.0 KiB — 89 ms — h2https://ajax.googleapis.com/ajax/libs/jquery/3.4.1/jquery.min.jsajax.googleapis.com/ajax/libs/jquer... https://ajax.googleapis.com/ajax/libs/jquery/3.4.1/jquery.min.js — 200 — 30.7 KiB — 22 ms — h2https://www.googletagmanager.com/gtag/js?id=UA-465405-9www.googletagmanager.com/gtag/js?id... https://www.googletagmanager.com/gtag/js?id=UA-465405-9 — 200 — 125.3 KiB — 41 ms — h2https://www.imo.org/Content/css/css/main.css?v=1.2www.imo.org/Content/css/css/main.cs... https://www.imo.org/Content/css/css/main.css?v=1.2 — 301 — 241 B — 26 ms — h2https://www.imo.org/Content/images/img/English_Colour_RGB_Horizontal.pngwww.imo.org/Content/images/img/Engl... https://www.imo.org/Content/images/img/English_Colour_RGB_Horizontal.png — 301 — 257 B — 26 ms — h2https://wwwcdn.imo.org/localresources/en/MediaCentre/WhatsNew/PublishingImages/LEG%20113%20PB_banner%20medium.jpgwwwcdn.imo.org/localresources/en/Me... https://wwwcdn.imo.org/localresources/en/MediaCentre/WhatsNew/PublishingImages/LEG%20113%20PB_banner%20medium.jpg — 200 — 976.6 KiB — 226 ms — h2https://www.imo.org/content/css/css/main.css?v=1.2www.imo.org/content/css/css/main.cs... https://www.imo.org/content/css/css/main.css?v=1.2 — 200 — 53.6 KiB — 38 ms — h2https://www.imo.org/content/images/img/english_colour_rgb_horizontal.pngwww.imo.org/content/images/img/engl... https://www.imo.org/content/images/img/english_colour_rgb_horizontal.png — 200 — 86.5 KiB — 34 ms — h2https://wwwcdn.imo.org/localresources/en/MediaCentre/PublishingImages/HNS%20PB%20Banner_A_medium.jpgwwwcdn.imo.org/localresources/en/Me... https://wwwcdn.imo.org/localresources/en/MediaCentre/PublishingImages/HNS%20PB%20Banner_A_medium.jpg — 200 — 1.7 MiB — 554 ms — h2https://wwwcdn.imo.org/localresources/en/MediaCentre/WhatsNew/PublishingImages/SG%20Statement_medium__%201.jpgwwwcdn.imo.org/localresources/en/Me... https://wwwcdn.imo.org/localresources/en/MediaCentre/WhatsNew/PublishingImages/SG%20Statement_medium__%201.jpg — 200 — 1.3 MiB — 750 ms — h2https://wwwcdn.imo.org/localresources/en/MediaCentre/WhatsNew/PublishingImages/FALConclusion.jpgwwwcdn.imo.org/localresources/en/Me... https://wwwcdn.imo.org/localresources/en/MediaCentre/WhatsNew/PublishingImages/FALConclusion.jpg — 200 — 447.9 KiB — 542 ms — h2https://www.imo.org/Scripts/js/vendors.jswww.imo.org/Scripts/js/vendors.js https://www.imo.org/Scripts/js/vendors.js — 301 — 235 B — 247 ms — h2https://www.imo.org/Scripts/js/theme.jswww.imo.org/Scripts/js/theme.js https://www.imo.org/Scripts/js/theme.js — 301 — 232 B — 247 ms — h2https://maps.googleapis.com/maps/api/js?key=AIzaSyCDYY_ECpWhLm56VGe6abMJ8Msj_Nt_8LMmaps.googleapis.com/maps/api/js?key... https://maps.googleapis.com/maps/api/js?key=AIzaSyCDYY_ECpWhLm56VGe6abMJ8Msj_Nt_8LM — 200 — 100.4 KiB — 113 ms — h2https://www.imo.org/Scripts/js/fbShare.jswww.imo.org/Scripts/js/fbShare.js https://www.imo.org/Scripts/js/fbShare.js — 301 — 236 B — 246 ms — h2https://www.imo.org/Scripts/js/d3.jswww.imo.org/Scripts/js/d3.js https://www.imo.org/Scripts/js/d3.js — 301 — 232 B — 247 ms — h2https://wwwcdn.imo.org/localresources/en/MediaCentre/WhatsNew/PublishingImages/Applications%20Now%20Open_GV_medium.jpgwwwcdn.imo.org/localresources/en/Me... https://wwwcdn.imo.org/localresources/en/MediaCentre/WhatsNew/PublishingImages/Applications%20Now%20Open_GV_medium.jpg — 200 — 1.3 MiB — 768 ms — h2https://wwwcdn.imo.org/localresources/en/MediaCentre/WhatsNew/PublishingImages/Comoros%20launches%20National%20Maritime%20Security%20Committee%20with%20IMO%20support_medium.jpgwwwcdn.imo.org/localresources/en/Me... https://wwwcdn.imo.org/localresources/en/MediaCentre/WhatsNew/PublishingImages/Comoros%20launches%20National%20Maritime%20Security%20Committee%20with%20IMO%20support_medium.jpg — 200 — 1.1 MiB — 703 ms — h2https://wwwcdn.imo.org/localresources/en/MediaCentre/PublishingImages/Vessel%20Image%2002.jpgwwwcdn.imo.org/localresources/en/Me... https://wwwcdn.imo.org/localresources/en/MediaCentre/PublishingImages/Vessel%20Image%2002.jpg — 200 — 2.8 MiB — 827 ms — h2https://wwwcdn.imo.org/localresources/en/MediaCentre/PublishingImages/Middle%20East%20Hot%20Topic%20thumbnail.jpgwwwcdn.imo.org/localresources/en/Me... https://wwwcdn.imo.org/localresources/en/MediaCentre/PublishingImages/Middle%20East%20Hot%20Topic%20thumbnail.jpg — 200 — 251.8 KiB — 148 ms — h2https://wwwcdn.imo.org/localresources/en/MediaCentre/PublishingImages/WMD%202026%20event%20page%20thumbnail.jpgwwwcdn.imo.org/localresources/en/Me... 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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 1409ms · 390KB · £15/mo
Unattributable
Other
Costly
Execution 532ms
Transfer 0 KB
Monthly Cost £6/mo
www.imo.org
Other
Costly
Execution 359ms
Transfer 18 KB
Monthly Cost £4/mo
www.imo.org
Other
Costly
Execution 242ms
Transfer 0 KB
Monthly Cost £3/mo
Google Tag Manager
Tag Manager
Optional
Execution 130ms
Transfer 125 KB
Unused 51%
Monthly Cost £1/mo
Google Tag Manager
Tag Manager
Optional
Execution 83ms
Transfer 146 KB
Unused 43%
Monthly Cost £1/mo
maps.googleapis.com
Other
Optional
Execution 62ms
Transfer 100 KB
Unused 65%
Monthly Cost £1/mo

These scripts may cost more than they're worth

  • Unattributable adds 532ms and costs ~£6/month
  • www.imo.org adds 359ms and costs ~£4/month
  • www.imo.org adds 242ms and costs ~£3/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

Unattributable takes 532ms 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.imo.org takes 359ms 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.imo.org takes 242ms 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

51% of Google Tag Manager's code is unused. The script may be loading features you don't use.

Why this matters

Bundle has high unused-code ratio — tree-shaking and route-splitting recover the wasted bytes.

Source: web.dev

65% of maps.googleapis.com's code is unused. The script may be loading features you don't use.

Why this matters

Bundle has high unused-code ratio — tree-shaking and route-splitting recover the wasted bytes.

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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