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https://oxfordlearnersdictionaries.com

Performance

· 15 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
77
GRADE
C
FIX
4
REVIEW
3
PASS
6
INFO
2

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

Mobile Desktop
76
Performance Overall performance score (0–100) based on Core Web Vitals and other metrics. 90+ is good.
84
Accessibility Measures how accessible the page is for users with disabilities. Checks color contrast, ARIA labels, and semantic HTML.
77
Best Practices Checks for modern web development best practices including HTTPS, no console errors, and secure JavaScript.
85
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.

1.99 s

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

2.42 s

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

8 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.

1.99 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.

2.52 s

Page Load Progression

467 ms
934 ms
1.4 s
1.9 s
2.3 s
2.8 s
3.3 s
3.7 s
Checks
15
6 PASS 3 REVIEW 4 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 (1.7 MiB of 1.7 MiB)
Info::
Third-party blocking time is low (0 ms)
100%
First-party Third-party
D
JS Bundles
Action
15 scripts, 449 KB unused
FIX
15 scripts, 449 KB unused
Warning::
https://securepubads.g.doubleclick.net/pagead/mana...: 141 KB unused (75%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://cdn.polarbyte.com/idm/old/pb.min.js: 109 KB unused (80%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.oxfordlearnersdictionaries.com/common....: 85 KB unused (76%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://cdn.polarbyte.com/idm/old/iaw.min.js: 43 KB unused (51%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://pagead2.googlesyndication.com/pagead/js/ad...: 35 KB unused (65%)
Consider code splitting or tree shaking to reduce unused code.
Info::
Total unused JavaScript: 449 KB
449 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://securepubads.g.doubleclick.net/pagead/managed/js/gpt/m202604210101/pubads_impl.js?cb=31098008188 KB141 KB (75%)✓3rd
https://cdn.polarbyte.com/idm/old/pb.min.js137 KB109 KB (80%)✓3rd
https://www.oxfordlearnersdictionaries.com/common.js?version=2.3.76112 KB85 KB (76%)✓3rd
https://cdn.polarbyte.com/idm/old/iaw.min.js85 KB43 KB (51%)✓3rd
https://pagead2.googlesyndication.com/pagead/js/adsbygoogle.js54 KB35 KB (65%)✓3rd
https://pagead2.googlesyndication.com/pagead/js/adsbygoogle.js0 KB35 KB (65%)✓3rd
data:text/javascript,10 KB—✓3rd
https://www.oxfordlearnersdictionaries.com/external/scripts/doubleclick.js?version=2.3.765 KB—✓3rd
https://www.google-analytics.com/analytics.js21 KB—✓3rd
https://securepubads.g.doubleclick.net/tag/js/gpt.js34 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

F
Page Weight Inventory
Action
65 resources · 1.7 MB · 449 KB savings available
FIX
65 resources · 1.7 MB · 449 KB savings available
Warning::
Page weight 686 KB over 1MB target
Got: 1.7 MB Expected: ≤ 1 MB
Info::
~449 KB of savings available
Warning::
64 third-party resources (100% of weight)
65 resources · 1.7 MiB · 64 third-party 686.4 KiB over 1MB target
Image 44% · 750.6 KiB
JavaScript 41% · 709.6 KiB
CSS 10% · 166.3 KiB
Font 3% · 43.8 KiB
Other 1% · 23.6 KiB
Document 1% · 16.5 KiB

~448.6 KiB of savings available

Remove unused JavaScript: 448.6 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
Page Weight Budget
Action
1.7 MB transferred, 65 requests
REVIEW
1.7 MB transferred, 65 requests
Info::
Page weighs 3.5 MB (1.7 MB transferred)
Warning::
JavaScript is 624 KB — consider code splitting or lazy loading
Large JavaScript bundles delay interactivity. Split code by route or defer non-critical scripts.
Got: 624 KB
Info::
65 HTTP requests
Info::
Estimated 0.35 g CO2 per page load
1.7 MB / 2.4 MB budget
1.7 MB transferred
65 requests
0.35 g CO2 per page load
Images 734.8 KiB 43%
JavaScript 623.9 KiB 36%
CSS 166.3 KiB 10%
Other 85.7 KiB 5%
Fonts 43.8 KiB 3%
Other 39.0 KiB 2%
HTML 16.3 KiB 1%
Other 670 B 0%
0 2.4 MB 4.9 MB
Approaching limit

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

C
Image Optimization
Action
30 images, 0 KB saveable
REVIEW
30 images, 0 KB saveable
Warning::
https://dtcfza6z1c8xn.cloudfront.net/OLD_home_Word... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.oxfordlearnersdictionaries.com/externa... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.oxfordlearnersdictionaries.com/externa... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://dtcfza6z1c8xn.cloudfront.net/OLD_WoTM_cult... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.oxfordlearnersdictionaries.com/externa... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.oxfordlearnersdictionaries.com/externa... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.oxfordlearnersdictionaries.com/externa... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.oxfordlearnersdictionaries.com/externa... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.oxfordlearnersdictionaries.com/externa... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.oxfordlearnersdictionaries.com/externa... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.oxfordlearnersdictionaries.com/externa... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://dtcfza6z1c8xn.cloudfront.net/OLD_home_newt... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://dtcfza6z1c8xn.cloudfront.net/2026_02_otelc... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.oxfordlearnersdictionaries.com/externa... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://dtcfza6z1c8xn.cloudfront.net/grammar-promo... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
30 images 735 KB
0 oversized -0 KB
29 legacy format
15 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

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

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+
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
432ms total JS execution
PASS
432ms total JS execution
Info::
https://www.oxfordlearnersdictionaries.com/: 133ms CPU time
Info::
Unattributable: 127ms CPU time
Info::
https://www.oxfordlearnersdictionaries.com/common....: 58ms CPU time
Info::
https://securepubads.g.doubleclick.net/pagead/mana...: 58ms CPU time
Info::
https://cdn.polarbyte.com/idm/old/pb.min.js: 57ms CPU time
Warning::
Third-party scripts: 432ms (100% of total)

Main Thread Breakdown

Script Evaluation 45% Other 23% Style & Layout 13% Script Parsing & Compilation 12% Rendering 4%
ScriptTotalScriptingParse/CompileParty
https://www.oxfordlearnersdictionaries.com/133ms34ms2ms3rd
Unattributable127ms17ms0ms3rd
https://www.oxfordlearnersdictionaries.com/common.js?version=2.3.7658ms33ms15ms3rd
https://securepubads.g.doubleclick.net/pagead/managed/js/gpt/m202604210101/pubads_impl.js?cb=3109800858ms39ms15ms3rd
https://cdn.polarbyte.com/idm/old/pb.min.js57ms44ms12ms3rd
A+
Font Loading
5 fonts (44 KB)
PASS
5 fonts (44 KB)
Info::
5 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

5

44 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 500 ms 1.0 s 1.5 s 2.0 s 2.5 s FCP 2.0 s LCP 2.4 shttps://fonts.gstatic.com/s/sourcesanspro/v23/6xK3dSBYKcSV-LCoeQqfX1RYOo3qOK7lujVj9w.woff26xK3dSBYKcSV-LCoeQqfX1R... https://fonts.gstatic.com/s/sourcesanspro/v23/6xK3dSBYKcSV-LCoeQqfX1RYOo3qOK7lujVj9w.woff2 — 14.5 KiB — 56 ms — font-display: swaphttps://fonts.gstatic.com/s/sourcesanspro/v23/6xKydSBYKcSV-LCoeQqfX1RYOo3i54rwlxdu3cOWxw.woff26xKydSBYKcSV-LCoeQqfX1R... https://fonts.gstatic.com/s/sourcesanspro/v23/6xKydSBYKcSV-LCoeQqfX1RYOo3i54rwlxdu3cOWxw.woff2 — 14.6 KiB — 40 ms — font-display: swaphttps://www.oxfordlearnersdictionaries.com/external/fonts/oup-icons.ttfoup-icons.ttf https://www.oxfordlearnersdictionaries.com/external/fonts/oup-icons.ttf — 419 B — 196 ms — font-display: swaphttps://fonts.gstatic.com/s/sourcesanspro/v23/6xK1dSBYKcSV-LCoeQqfX1RYOo3qPZ7nsDJB9cme.woff26xK1dSBYKcSV-LCoeQqfX1R... https://fonts.gstatic.com/s/sourcesanspro/v23/6xK1dSBYKcSV-LCoeQqfX1RYOo3qPZ7nsDJB9cme.woff2 — 13.9 KiB — 49 ms — font-display: swaphttps://www.oxfordlearnersdictionaries.com/external/fonts/oup-icons.woffoup-icons.woff https://www.oxfordlearnersdictionaries.com/external/fonts/oup-icons.woff — 416 B — 143 ms — font-display: swap
6xK3dSBYKcSV-LCoeQqfX1R... woff2 swap
Size 15 KB
Load time 56 ms
Start 975 ms
Risk FOUT — text flashes from fallback to web font
6xKydSBYKcSV-LCoeQqfX1R... woff2 swap
Size 15 KB
Load time 40 ms
Start 975 ms
Risk FOUT — text flashes from fallback to web font
oup-icons.ttf ttf swap
Size 0 KB
Load time 196 ms
Start 976 ms
Risk FOUT — text flashes from fallback to web font
  • Convert to woff2 for ~30% smaller file size
6xK1dSBYKcSV-LCoeQqfX1R... woff2 swap
Size 14 KB
Load time 49 ms
Start 976 ms
Risk FOUT — text flashes from fallback to web font
oup-icons.woff woff swap
Size 0 KB
Load time 143 ms
Start 1.2 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)
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
65 requests over 1442ms
INFO
0 ms 500 ms 1.0 s 1.5 s 2.0 s 2.5 s FCP 2.0 s LCP 2.4 shttps://oxfordlearnersdictionaries.com// https://oxfordlearnersdictionaries.com/ — 301 — 211 B — 113 ms — http/1.1https://www.oxfordlearnersdictionaries.com/www.oxfordlearnersdictionaries.com/ https://www.oxfordlearnersdictionaries.com/ — 200 — 16.3 KiB — 399 ms — h2https://cdn.cookielaw.org/consent/tcf.stub.jscdn.cookielaw.org/consent/tcf.stub.... https://cdn.cookielaw.org/consent/tcf.stub.js — -1 — 0 B — 64 ms — https://cdn.cookielaw.org/scripttemplates/otSDKStub.jscdn.cookielaw.org/scripttemplates/o... https://cdn.cookielaw.org/scripttemplates/otSDKStub.js — -1 — 0 B — 65 ms — https://cdn.polarbyte.com/idm/old/iaw.min.csscdn.polarbyte.com/idm/old/iaw.min.c... https://cdn.polarbyte.com/idm/old/iaw.min.css — 200 — 1.4 KiB — 50 ms — h3https://cdn.polarbyte.com/idm/old/adserver.min.csscdn.polarbyte.com/idm/old/adserver.... https://cdn.polarbyte.com/idm/old/adserver.min.css — 200 — 494 B — 48 ms — h3https://www.google-analytics.com/analytics.jswww.google-analytics.com/analytics.... https://www.google-analytics.com/analytics.js — 200 — 20.9 KiB — 122 ms — h2https://www.oxfordlearnersdictionaries.com/external/styles/interface.css?version=2.3.76www.oxfordlearnersdictionaries.com/... https://www.oxfordlearnersdictionaries.com/external/styles/interface.css?version=2.3.76 — 200 — 105.4 KiB — 300 ms — h2https://www.oxfordlearnersdictionaries.com/external/styles/autocomplete.css?version=2.3.76www.oxfordlearnersdictionaries.com/... https://www.oxfordlearnersdictionaries.com/external/styles/autocomplete.css?version=2.3.76 — 200 — 3.4 KiB — 299 ms — h2https://www.oxfordlearnersdictionaries.com/external/styles/grid.css?version=2.3.76www.oxfordlearnersdictionaries.com/... https://www.oxfordlearnersdictionaries.com/external/styles/grid.css?version=2.3.76 — 200 — 1.5 KiB — 299 ms — h2https://www.oxfordlearnersdictionaries.com/external/styles/footer.css?version=2.3.76www.oxfordlearnersdictionaries.com/... https://www.oxfordlearnersdictionaries.com/external/styles/footer.css?version=2.3.76 — 200 — 4.3 KiB — 297 ms — h2https://www.oxfordlearnersdictionaries.com/external/styles/header.css?version=2.3.76www.oxfordlearnersdictionaries.com/... https://www.oxfordlearnersdictionaries.com/external/styles/header.css?version=2.3.76 — 200 — 20.0 KiB — 297 ms — h2https://www.oxfordlearnersdictionaries.com/external/styles/responsive.css?version=2.3.76www.oxfordlearnersdictionaries.com/... https://www.oxfordlearnersdictionaries.com/external/styles/responsive.css?version=2.3.76 — 200 — 27.2 KiB — 102 ms — h2https://www.oxfordlearnersdictionaries.com/external/images/OLD_logo.svg?version=2.3.76www.oxfordlearnersdictionaries.com/... https://www.oxfordlearnersdictionaries.com/external/images/OLD_logo.svg?version=2.3.76 — 200 — 10.0 KiB — 296 ms — h2https://dtcfza6z1c8xn.cloudfront.net/2026_02_otelc-research-image.pngdtcfza6z1c8xn.cloudfront.net/2026_0... https://dtcfza6z1c8xn.cloudfront.net/2026_02_otelc-research-image.png — 200 — 26.5 KiB — 63 ms — h2data:text/javascript,1data:text/javascript,1 data:text/javascript,1 — 200 — 0 B — 0 ms — datahttps://dtcfza6z1c8xn.cloudfront.net/OLD_home_Word_lists_panel5.pngdtcfza6z1c8xn.cloudfront.net/OLD_ho... https://dtcfza6z1c8xn.cloudfront.net/OLD_home_Word_lists_panel5.png — 200 — 20.1 KiB — 24 ms — h2https://dtcfza6z1c8xn.cloudfront.net/OLD_WoTM_culture_war.pngdtcfza6z1c8xn.cloudfront.net/OLD_Wo... https://dtcfza6z1c8xn.cloudfront.net/OLD_WoTM_culture_war.png — 200 — 122.2 KiB — 43 ms — h2https://dtcfza6z1c8xn.cloudfront.net/OLD_home_newtopicsfeature.pngdtcfza6z1c8xn.cloudfront.net/OLD_ho... https://dtcfza6z1c8xn.cloudfront.net/OLD_home_newtopicsfeature.png — 200 — 66.2 KiB — 26 ms — h2https://www.oxfordlearnersdictionaries.com/common.js?version=2.3.76www.oxfordlearnersdictionaries.com/... https://www.oxfordlearnersdictionaries.com/common.js?version=2.3.76 — 200 — 112.1 KiB — 232 ms — h2https://www.oxfordlearnersdictionaries.com/external/scripts/doubleclick.js?version=2.3.76www.oxfordlearnersdictionaries.com/... https://www.oxfordlearnersdictionaries.com/external/scripts/doubleclick.js?version=2.3.76 — 200 — 4.8 KiB — 103 ms — h2https://fonts.googleapis.com/css?family=Source+Sans+Pro:400,400i,600,600i&display=swapfonts.googleapis.com/css?family=Sou... https://fonts.googleapis.com/css?family=Source+Sans+Pro:400,400i,600,600i&display=swap — 200 — 1.3 KiB — 89 ms — h2https://cdn.polarbyte.com/idm/old/pb.min.jscdn.polarbyte.com/idm/old/pb.min.js https://cdn.polarbyte.com/idm/old/pb.min.js — 200 — 136.9 KiB — 98 ms — h3https://securepubads.g.doubleclick.net/tag/js/gpt.jssecurepubads.g.doubleclick.net/tag/... https://securepubads.g.doubleclick.net/tag/js/gpt.js — 200 — 34.1 KiB — 64 ms — h3https://html-load.com/sdk.jshtml-load.com/sdk.js https://html-load.com/sdk.js — 200 — 42.2 KiB — 131 ms — h2https://cdn.polarbyte.com/idm/old/iaw.min.jscdn.polarbyte.com/idm/old/iaw.min.j... https://cdn.polarbyte.com/idm/old/iaw.min.js — 200 — 85.2 KiB — 98 ms — h3https://dtcfza6z1c8xn.cloudfront.net/grammar-promo-square.pngdtcfza6z1c8xn.cloudfront.net/gramma... https://dtcfza6z1c8xn.cloudfront.net/grammar-promo-square.png — 200 — 103.6 KiB — 34 ms — h2https://www.oxfordlearnersdictionaries.com/external/images/home_2020/OLD_home_productsOALD.png?version=2.3.76www.oxfordlearnersdictionaries.com/... https://www.oxfordlearnersdictionaries.com/external/images/home_2020/OLD_home_productsOALD.png?version=2.3.76 — 200 — 17.9 KiB — 215 ms — h2https://www.oxfordlearnersdictionaries.com/external/images/home_2020/OLD_home_productsOLDAE.png?version=2.3.76www.oxfordlearnersdictionaries.com/... https://www.oxfordlearnersdictionaries.com/external/images/home_2020/OLD_home_productsOLDAE.png?version=2.3.76 — 200 — 78.1 KiB — 130 ms — h2https://www.oxfordlearnersdictionaries.com/external/images/home_2020/OLD_home_productsPEU.png?version=2.3.76www.oxfordlearnersdictionaries.com/... https://www.oxfordlearnersdictionaries.com/external/images/home_2020/OLD_home_productsPEU.png?version=2.3.76 — 200 — 29.1 KiB — 112 ms — h2
0 ms 500 ms 1.0 s 1.5 s 2.0 s 2.5 s FCP 2.0 s LCP 2.4 shttps://oxfordlearnersdictionaries.com// https://oxfordlearnersdictionaries.com/ — 301 — 211 B — 113 ms — http/1.1https://www.oxfordlearnersdictionaries.com/www.oxfordlearnersdictionaries.com/ https://www.oxfordlearnersdictionaries.com/ — 200 — 16.3 KiB — 399 ms — h2https://cdn.cookielaw.org/consent/tcf.stub.jscdn.cookielaw.org/consent/tcf.stub.... https://cdn.cookielaw.org/consent/tcf.stub.js — -1 — 0 B — 64 ms — https://cdn.cookielaw.org/scripttemplates/otSDKStub.jscdn.cookielaw.org/scripttemplates/o... https://cdn.cookielaw.org/scripttemplates/otSDKStub.js — -1 — 0 B — 65 ms — https://cdn.polarbyte.com/idm/old/iaw.min.csscdn.polarbyte.com/idm/old/iaw.min.c... https://cdn.polarbyte.com/idm/old/iaw.min.css — 200 — 1.4 KiB — 50 ms — h3https://cdn.polarbyte.com/idm/old/adserver.min.csscdn.polarbyte.com/idm/old/adserver.... https://cdn.polarbyte.com/idm/old/adserver.min.css — 200 — 494 B — 48 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 432ms · 453KB · £4/mo
www.oxfordlearnersdictionaries.com
Other
Optional
Execution 133ms
Transfer 16 KB
Monthly Cost £1/mo
Unattributable
Other
Optional
Execution 127ms
Transfer 0 KB
Monthly Cost £1/mo
www.oxfordlearnersdictionaries.com
Other
Optional
Execution 58ms
Transfer 112 KB
Unused 76%
Monthly Cost £1/mo
securepubads.g.doubleclick.net
Other
Optional
Execution 58ms
Transfer 188 KB
Unused 75%
Monthly Cost £1/mo
cdn.polarbyte.com
Other
Optional
Execution 57ms
Transfer 137 KB
Unused 80%
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.

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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

76% of www.oxfordlearnersdictionaries.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

75% of securepubads.g.doubleclick.net'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

80% of cdn.polarbyte.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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