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Performance

· 17 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
84
GRADE
B
FIX
2
REVIEW
6
PASS
7
INFO
2

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

Mobile Desktop
67
Performance Overall performance score (0–100) based on Core Web Vitals and other metrics. 90+ is good.
95
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.
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.

3.27 s

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

4.44 s

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

58 ms

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

0.125

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

7.18 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.

6.49 s

Page Load Progression

644 ms
1.3 s
1.9 s
2.6 s
3.2 s
3.9 s
4.5 s
5.2 s
Checks
17
7 PASS 6 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 (1.2 MiB of 1.2 MiB)
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.

B
Page Weight Budget
1.2 MB transferred, 35 requests
REVIEW
1.2 MB transferred, 35 requests
Info::
Page weighs 2.1 MB (1.2 MB transferred)
Info::
Fonts are 320 KB — consider subsetting or using system fonts
Subset fonts to include only used characters, or switch to system font stacks.
Got: 320 KB
Info::
35 HTTP requests
Info::
Estimated 0.26 g CO2 per page load
1.2 MB / 2.4 MB budget
1.2 MB transferred
35 requests
0.26 g CO2 per page load
Images 635.4 KiB 50%
Fonts 320.2 KiB 25%
JavaScript 228.3 KiB 18%
Other 37.5 KiB 3%
CSS 37.4 KiB 3%
HTML 9.0 KiB 1%
Other 6.0 KiB 0%
Other 548 B 0%
0 2.4 MB 4.9 MB
Under budget

Subset fonts to include only used characters, or switch to system font stacks.

Why this matters

Font payload is large — subset to used glyphs only, or fall back to system fonts (zero load time).

Source: web.dev font loading

C
Image Optimization
Action
12 images, 0 KB saveable
REVIEW
12 images, 0 KB saveable
Warning::
https://acxngcvroo.cloudimg.io/v7/https://www.embl... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://acxngcvroo.cloudimg.io/v7/https://www.embl... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://acxngcvroo.cloudimg.io/v7/https://www.embl... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://acxngcvroo.cloudimg.io/v7/https://www.embl... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://acxngcvroo.cloudimg.io/v7/https://www.embl... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
12 images 635 KB
0 oversized -0 KB
8 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

B
JS Execution Cost
999ms total JS execution
REVIEW
999ms total JS execution
Warning::
https://www.ebi.ac.uk/: 411ms CPU time
Warning::
https://www.googletagmanager.com/gtag/js?id=G-DGQJ...: 252ms CPU time
Info::
Unattributable: 190ms CPU time
Info::
https://www.ebi.ac.uk/scripts/scripts.js?: 91ms CPU time
Info::
https://ebi.emblstatic.net/web_guidelines/EBI-Fram...: 55ms CPU time
Warning::
Third-party scripts: 999ms (100% of total)

Main Thread Breakdown

Script Evaluation 30% Style & Layout 29% Other 24% Rendering 7% Script Parsing & Compilation 6% Parse HTML & CSS 3%
ScriptTotalScriptingParse/CompileParty
https://www.ebi.ac.uk/411ms8ms2ms3rd
https://www.googletagmanager.com/gtag/js?id=G-DGQJ9J085B252ms198ms33ms3rd
Unattributable190ms6ms0ms3rd
https://www.ebi.ac.uk/scripts/scripts.js?91ms51ms21ms3rd
https://ebi.emblstatic.net/web_guidelines/EBI-Framework/v1.4/js/script.js55ms42ms3ms3rd
C
JS Bundles
Action
6 scripts, 90 KB unused
REVIEW
6 scripts, 90 KB unused
Warning::
https://www.googletagmanager.com/gtag/js?id=G-DGQJ...: 66 KB unused (42%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.ebi.ac.uk/scripts/scripts.js?: 25 KB unused (62%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.ebi.ac.uk/scripts/scripts.js?: unminified — 16 KB could be saved
Warning::
https://cdnjs.cloudflare.com/ajax/libs/alpinejs/3....: unminified — 5 KB could be saved
Info::
Total unused JavaScript: 90 KB
90 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://www.googletagmanager.com/gtag/js?id=G-DGQJ9J085B159 KB66 KB (42%)✓3rd
https://www.ebi.ac.uk/scripts/scripts.js?40 KB25 KB (62%)✗3rd
https://cdnjs.cloudflare.com/ajax/libs/alpinejs/3.10.2/cdn.js19 KB—✗3rd
https://ebi.emblstatic.net/web_guidelines/EBI-Framework/v1.4/js/script.js11 KB—✗3rd
https://ebi.emblstatic.net/announcements.js1 KB—✓3rd
https://embl-communications.github.io/embl-notifcations-fallback/notifications.js1 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

C
Page Weight Inventory
Action
35 resources · 1.2 MB · 90 KB savings available
REVIEW
35 resources · 1.2 MB · 90 KB savings available
Warning::
Page weight 250 KB over 1MB target
Got: 1.2 MB Expected: ≤ 1 MB
Info::
~90 KB of savings available
Warning::
34 third-party resources (100% of weight)
35 resources · 1.2 MiB · 34 third-party 250.4 KiB over 1MB target
Image 53% · 672.8 KiB
Font 25% · 320.2 KiB
JavaScript 18% · 230.1 KiB
CSS 3% · 37.4 KiB
Document 1% · 12.1 KiB
Other 0% · 1.7 KiB

~90.3 KiB of savings available

Remove unused JavaScript: 90.3 KiB
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
5 fonts (320 KB)
PASS
5 fonts (320 KB)
Info::
5 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

5

320 KB total

Render-blocking

0

of 5

Dominant font-display

swap

Most common across fonts

Font loading timeline
Transfer FOIT (block) FOUT (swap)
0 ms 1.0 s 2.0 s 3.0 s 4.0 s 5.0 s FCP 3.3 s LCP 4.4 shttps://www.ebi.ac.uk/assets/vf-font-plex-sans/assets/IBM-Plex-Sans/fonts/complete/woff/IBMPlexSans-Bold.woffIBMPlexSans-Bold.woff https://www.ebi.ac.uk/assets/vf-font-plex-sans/assets/IBM-Plex-Sans/fonts/complete/woff/IBMPlexSans-Bold.woff — 74.8 KiB — 1.2 s — font-display: swaphttps://www.ebi.ac.uk/assets/vf-font-plex-sans/assets/IBM-Plex-Sans/fonts/complete/woff/IBMPlexSans-Medium.woffIBMPlexSans-Medium.woff https://www.ebi.ac.uk/assets/vf-font-plex-sans/assets/IBM-Plex-Sans/fonts/complete/woff/IBMPlexSans-Medium.woff — 79.5 KiB — 695 ms — font-display: swaphttps://www.ebi.ac.uk/assets/vf-font-plex-sans/assets/IBM-Plex-Sans/fonts/complete/woff/IBMPlexSans-Regular.woffIBMPlexSans-Regular.woff https://www.ebi.ac.uk/assets/vf-font-plex-sans/assets/IBM-Plex-Sans/fonts/complete/woff/IBMPlexSans-Regular.woff — 75.3 KiB — 839 ms — font-display: swaphttps://ebi.emblstatic.net/web_guidelines/EBI-Icon-fonts/v1.3/EBI-Generic/fonts/EBI-Generic.woff2EBI-Generic.woff2 https://ebi.emblstatic.net/web_guidelines/EBI-Icon-fonts/v1.3/EBI-Generic/fonts/EBI-Generic.woff2 — 10.8 KiB — 45 ms — font-display: swaphttps://www.ebi.ac.uk/assets/vf-font-plex-sans/assets/IBM-Plex-Sans/fonts/complete/woff/IBMPlexSans-SemiBold.woffIBMPlexSans-SemiBold.woff https://www.ebi.ac.uk/assets/vf-font-plex-sans/assets/IBM-Plex-Sans/fonts/complete/woff/IBMPlexSans-SemiBold.woff — 79.8 KiB — 1.1 s — font-display: swap
IBMPlexSans-Bold.woff woff swap
Size 75 KB
Load time 1.2 s
Start 3.9 s
Risk FOUT — text flashes from fallback to web font
  • Convert to woff2 for ~30% smaller file size
IBMPlexSans-Medium.woff woff swap
Size 79 KB
Load time 695 ms
Start 3.9 s
Risk FOUT — text flashes from fallback to web font
  • Convert to woff2 for ~30% smaller file size
IBMPlexSans-Regular.woff woff swap
Size 75 KB
Load time 839 ms
Start 3.9 s
Risk FOUT — text flashes from fallback to web font
  • Convert to woff2 for ~30% smaller file size
EBI-Generic.woff2 woff2 swap
Size 11 KB
Load time 45 ms
Start 4.1 s
Risk FOUT — text flashes from fallback to web font
IBMPlexSans-SemiBold.woff woff swap
Size 80 KB
Load time 1.1 s
Start 4.2 s
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 ~93 KB and ~186 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
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
35 requests over 5408ms
INFO
0 ms 1.0 s 2.0 s 3.0 s 4.0 s 5.0 s FCP 3.3 s LCP 4.4 shttps://ebi.ac.uk// https://ebi.ac.uk/ — 301 — 68 B — 115 ms — h2https://www.ebi.ac.uk/www.ebi.ac.uk/ https://www.ebi.ac.uk/ — 200 — 9.0 KiB — 2.7 s — h2https://www.ebi.ac.uk/css/styles.css?www.ebi.ac.uk/css/styles.css? https://www.ebi.ac.uk/css/styles.css? — 200 — 25.3 KiB — 1.0 s — h2https://cdnjs.cloudflare.com/ajax/libs/alpinejs/3.10.2/cdn.jscdnjs.cloudflare.com/ajax/libs/alpi... https://cdnjs.cloudflare.com/ajax/libs/alpinejs/3.10.2/cdn.js — 200 — 18.7 KiB — 94 ms — h3https://assets.emblstatic.net/vf/v2.5.24/assets/ebi-header-footer/ebi-header-footer.cssassets.emblstatic.net/vf/v2.5.24/as... https://assets.emblstatic.net/vf/v2.5.24/assets/ebi-header-footer/ebi-header-footer.css — 200 — 4.1 KiB — 120 ms — h2https://acxngcvroo.cloudimg.io/v7/https://www.embl.org/files/wp-content/uploads/2020/04/logo-of-icons.pngacxngcvroo.cloudimg.io/v7/https://w... https://acxngcvroo.cloudimg.io/v7/https://www.embl.org/files/wp-content/uploads/2020/04/logo-of-icons.png — 200 — 8.5 KiB — 152 ms — h2https://www.ebi.ac.uk/scripts/scripts.js?www.ebi.ac.uk/scripts/scripts.js? https://www.ebi.ac.uk/scripts/scripts.js? — 200 — 39.9 KiB — 1.2 s — h2https://ebi.emblstatic.net/web_guidelines/EBI-Icon-fonts/v1.3/fonts.cssebi.emblstatic.net/web_guidelines/E... https://ebi.emblstatic.net/web_guidelines/EBI-Icon-fonts/v1.3/fonts.css — 200 — 8.0 KiB — 114 ms — h2https://ebi.emblstatic.net/web_guidelines/EBI-Framework/v1.4/js/script.jsebi.emblstatic.net/web_guidelines/E... https://ebi.emblstatic.net/web_guidelines/EBI-Framework/v1.4/js/script.js — 200 — 11.2 KiB — 115 ms — h2https://www.googletagmanager.com/gtag/js?id=G-DGQJ9J085Bwww.googletagmanager.com/gtag/js?id... https://www.googletagmanager.com/gtag/js?id=G-DGQJ9J085B — 200 — 158.5 KiB — 181 ms — h2https://acxngcvroo.cloudimg.io/v7/www.embl.org/files/wp-content/uploads/EMBL-EBI-home-hero-cells_2021-1-scaled.jpegacxngcvroo.cloudimg.io/v7/www.embl.... https://acxngcvroo.cloudimg.io/v7/www.embl.org/files/wp-content/uploads/EMBL-EBI-home-hero-cells_2021-1-scaled.jpeg — 200 — 51.3 KiB — 21 ms — h2data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='140' height='140'%3E%3Cpath d='…www.w3.org/2000/svg' width='140' he... data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='140' height='140'%3E%3Cpath d='… — 200 — 0 B — 0 ms — datahttps://acxngcvroo.cloudimg.io/v7/https://www.embl.org/editorhub/wp-content/uploads/2026/03/Highlights-Cover-2025-Hero-2000x400px-v1.jpgacxngcvroo.cloudimg.io/v7/https://w... https://acxngcvroo.cloudimg.io/v7/https://www.embl.org/editorhub/wp-content/uploads/2026/03/Highlights-Cover-2025-Hero-2000x400px-v1.jpg — 200 — 91.9 KiB — 15 ms — h3https://acxngcvroo.cloudimg.io/v7/www.embl.org/files/wp-content/uploads/Screenshot-2021-03-08-at-08.44.32.pngacxngcvroo.cloudimg.io/v7/www.embl.... https://acxngcvroo.cloudimg.io/v7/www.embl.org/files/wp-content/uploads/Screenshot-2021-03-08-at-08.44.32.png — 200 — 11.7 KiB — 59 ms — h3https://www.embl.org/editorhub/wp-content/uploads/2025/04/Training-stock-images-324-768x512.jpgwww.embl.org/editorhub/wp-content/u... https://www.embl.org/editorhub/wp-content/uploads/2025/04/Training-stock-images-324-768x512.jpg — 200 — 95.1 KiB — 312 ms — h2https://www.embl.org/editorhub/wp-content/uploads/2025/04/EMBL-EBI-Data-Centre-16-768x512.jpgwww.embl.org/editorhub/wp-content/u... https://www.embl.org/editorhub/wp-content/uploads/2025/04/EMBL-EBI-Data-Centre-16-768x512.jpg — 200 — 151.5 KiB — 343 ms — h2https://www.embl.org/editorhub/wp-content/uploads/2025/04/EMBL-EBI-30th-anniversary-81-768x512.jpgwww.embl.org/editorhub/wp-content/u... https://www.embl.org/editorhub/wp-content/uploads/2025/04/EMBL-EBI-30th-anniversary-81-768x512.jpg — 200 — 135.2 KiB — 339 ms — h2https://www.ebi.ac.uk/assets/vf-font-plex-sans/assets/IBM-Plex-Sans/fonts/complete/woff/IBMPlexSans-Bold.woffwww.ebi.ac.uk/assets/vf-font-plex-s... https://www.ebi.ac.uk/assets/vf-font-plex-sans/assets/IBM-Plex-Sans/fonts/complete/woff/IBMPlexSans-Bold.woff — 200 — 74.8 KiB — 1.2 s — h2https://www.ebi.ac.uk/assets/vf-font-plex-sans/assets/IBM-Plex-Sans/fonts/complete/woff/IBMPlexSans-Medium.woffwww.ebi.ac.uk/assets/vf-font-plex-s... https://www.ebi.ac.uk/assets/vf-font-plex-sans/assets/IBM-Plex-Sans/fonts/complete/woff/IBMPlexSans-Medium.woff — 200 — 79.5 KiB — 695 ms — h2https://www.ebi.ac.uk/assets/vf-font-plex-sans/assets/IBM-Plex-Sans/fonts/complete/woff/IBMPlexSans-Regular.woffwww.ebi.ac.uk/assets/vf-font-plex-s... https://www.ebi.ac.uk/assets/vf-font-plex-sans/assets/IBM-Plex-Sans/fonts/complete/woff/IBMPlexSans-Regular.woff — 200 — 75.3 KiB — 839 ms — h2https://www.embl.org/api/v1/pattern.html?pattern=vf-news-item-default&filter-content-type=article&filter-field-value[field_target_display]=both,embl-ebi&sort-field-value[created]=DESC&limit=4&hide[body]&site=embl-ebi&source=contenthubwww.embl.org/api/v1/pattern.html?pa... https://www.embl.org/api/v1/pattern.html?pattern=vf-news-item-default&filter-content-type=article&filter-field-value[field_target_display]=both,embl-ebi&sort-field-value[created]=DESC&limit=4&hide[body]&site=embl-ebi&source=contenthub — 200 — 1.6 KiB — 130 ms — h2https://www.embl.org/api/v1/pattern.html?filter-content-type=article&filter-id=106902&pattern=node-body&source=contenthubwww.embl.org/api/v1/pattern.html?fi... https://www.embl.org/api/v1/pattern.html?filter-content-type=article&filter-id=106902&pattern=node-body&source=contenthub — 200 — 1.5 KiB — 142 ms — h2https://ebi.emblstatic.net/announcements.jsebi.emblstatic.net/announcements.js https://ebi.emblstatic.net/announcements.js — 200 — 1.1 KiB — 134 ms — h2https://ebi.emblstatic.net/web_guidelines/EBI-Icon-fonts/v1.3/EBI-Generic/fonts/EBI-Generic.woff2ebi.emblstatic.net/web_guidelines/E... https://ebi.emblstatic.net/web_guidelines/EBI-Icon-fonts/v1.3/EBI-Generic/fonts/EBI-Generic.woff2 — 200 — 10.8 KiB — 45 ms — h2https://region1.google-analytics.com/g/collect?v=2&tid=G-DGQJ9J085B&gtm=45je64k1v890101087za200zd890101087&_p=1776897485695&gcd=13l3l3l2l1l1&npa=1&dma_cps=a&dma=1&are=1&cid=646890531.1776897486&frm=0&pscdl=noapi&rcb=15&sr=412x823&uaa=&uab=64&uafvl=Chromium%3B147.0.7727.101%7CNot.A%252FBrand%3B8.0.0.0&uam=moto%20g%20power%20(2022)&uamb=1&uap=Android&uapv=11.0&uaw=0&ul=en-us&_s=1&tag_exp=0~115616986~115938466~115938468~117266400~117384406~117512542&sid=1776897485&sct=1&seg=0&dl=https%3A%2F%2Fwww.ebi.ac.uk%2F&dt=EMBL-EBI%20homepage%20%7C%20EMBL-EBI&en=page_view&_fv=1&_nsi=1&_ss=1&_ee=1&tfd=4119region1.google-analytics.com/g/coll... https://region1.google-analytics.com/g/collect?v=2&tid=G-DGQJ9J085B&gtm=45je64k1v890101087za200zd890101087&_p=1776897485695&gcd=13l3l3l2l1l1&npa=1&dma_cps=a&dma=1&are=1&cid=646890531.1776897486&frm=0&pscdl=noapi&rcb=15&sr=412x823&uaa=&uab=64&uafvl=Chromium%3B147.0.7727.101%7CNot.A%252FBrand%3B8.0.0.0&uam=moto%20g%20power%20(2022)&uamb=1&uap=Android&uapv=11.0&uaw=0&ul=en-us&_s=1&tag_exp=0~115616986~115938466~115938468~117266400~117384406~117512542&sid=1776897485&sct=1&seg=0&dl=https%3A%2F%2Fwww.ebi.ac.uk%2F&dt=EMBL-EBI%20homepage%20%7C%20EMBL-EBI&en=page_view&_fv=1&_nsi=1&_ss=1&_ee=1&tfd=4119 — 204 — 548 B — 115 ms — h2https://acxngcvroo.cloudimg.io/v7/https://www.embl.org/news/wp-content/uploads/2026/04/DToL.jpg?w=600&h=400&force_format=jpeg&q=30acxngcvroo.cloudimg.io/v7/https://w... https://acxngcvroo.cloudimg.io/v7/https://www.embl.org/news/wp-content/uploads/2026/04/DToL.jpg?w=600&h=400&force_format=jpeg&q=30 — 200 — 14.0 KiB — 22 ms — h3https://acxngcvroo.cloudimg.io/v7/https://www.embl.org/news/wp-content/uploads/2026/02/2026-Bertha-Guadalupe-Rueda-Zarazua-profile-22-1.jpg?w=600&h=400&force_format=jpeg&q=30acxngcvroo.cloudimg.io/v7/https://w... https://acxngcvroo.cloudimg.io/v7/https://www.embl.org/news/wp-content/uploads/2026/02/2026-Bertha-Guadalupe-Rueda-Zarazua-profile-22-1.jpg?w=600&h=400&force_format=jpeg&q=30 — 200 — 24.2 KiB — 18 ms — h3https://acxngcvroo.cloudimg.io/v7/https://www.embl.org/news/wp-content/uploads/2026/03/STP-image-1-News-graphic-with-image-placeholder.png?w=600&h=400&force_format=jpeg&q=30acxngcvroo.cloudimg.io/v7/https://w... https://acxngcvroo.cloudimg.io/v7/https://www.embl.org/news/wp-content/uploads/2026/03/STP-image-1-News-graphic-with-image-placeholder.png?w=600&h=400&force_format=jpeg&q=30 — 200 — 26.5 KiB — 29 ms — 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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 999ms · 219KB · £10/mo
www.ebi.ac.uk
Other
Costly
Execution 411ms
Transfer 9 KB
Monthly Cost £4/mo
Google Tag Manager
Tag Manager
Costly
Execution 252ms
Transfer 159 KB
Unused 42%
Monthly Cost £3/mo
Unattributable
Other
Optional
Execution 190ms
Transfer 0 KB
Monthly Cost £2/mo
www.ebi.ac.uk
Other
Optional
Execution 91ms
Transfer 40 KB
Unused 62%
Monthly Cost £1/mo
ebi.emblstatic.net
Other
Optional
Execution 55ms
Transfer 11 KB
Monthly Cost £1/mo

These scripts may cost more than they're worth

  • www.ebi.ac.uk adds 411ms and costs ~£4/month
  • Google Tag Manager adds 252ms 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

www.ebi.ac.uk takes 411ms 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

Google Tag Manager takes 252ms 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

62% of www.ebi.ac.uk'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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