Skip to content
https://rsc.org

Performance

· 17 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
84
GRADE
B
FIX
2
REVIEW
5
PASS
8
INFO
2

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

Mobile Desktop
64
Performance Overall performance score (0–100) based on Core Web Vitals and other metrics. 90+ is good.
100
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.

3.95 s

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

7.55 s

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

152 ms

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

0.044

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

3.95 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.

8.88 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
8 PASS 5 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 (1.0 MiB of 1.0 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
1.0 MB transferred, 45 requests
REVIEW
1.0 MB transferred, 45 requests
Info::
Page weighs 2.7 MB (1.0 MB transferred)
Warning::
JavaScript is 502 KB — consider code splitting or lazy loading
Large JavaScript bundles delay interactivity. Split code by route or defer non-critical scripts.
Got: 502 KB
Info::
45 HTTP requests
Info::
Estimated 0.22 g CO2 per page load
1.0 MB / 2.4 MB budget
1.0 MB transferred
45 requests
0.22 g CO2 per page load
JavaScript 502.0 KiB 47%
Images 392.0 KiB 37%
Fonts 70.1 KiB 7%
CSS 36.9 KiB 3%
Other 34.1 KiB 3%
HTML 19.0 KiB 2%
Other 3.7 KiB 0%
Other 3.2 KiB 0%
Other 677 B 0%
0 2.4 MB 4.9 MB
Under budget

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
12 images, 0 KB saveable
REVIEW
12 images, 0 KB saveable
Warning::
https://www.rsc.org/getContentAsset/2a7615fb-391d-... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.rsc.org/getContentAsset/49ba6bc4-303d-... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
12 images 392 KB
0 oversized -0 KB
7 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
1163ms total JS execution
REVIEW
1163ms total JS execution
Warning::
Unattributable: 380ms CPU time
Warning::
https://www.googletagmanager.com/gtm.js?id=GTM-NWX...: 333ms CPU time
Info::
https://www.rsc.org/: 238ms CPU time
Info::
https://cdn-ukwest.onetrust.com/scripttemplates/20...: 135ms CPU time
Info::
https://www.rsc.org/scripts/360.js: 76ms CPU time
Warning::
Third-party scripts: 1163ms (100% of total)

Main Thread Breakdown

Script Evaluation 48% Other 26% Script Parsing & Compilation 10% Style & Layout 10% Rendering 3% Parse HTML & CSS 3%
ScriptTotalScriptingParse/CompileParty
Unattributable380ms101ms0ms3rd
https://www.googletagmanager.com/gtm.js?id=GTM-NWXSBHNW333ms269ms44ms3rd
https://www.rsc.org/238ms9ms3ms3rd
https://cdn-ukwest.onetrust.com/scripttemplates/202505.2.0/otBannerSdk.js135ms68ms43ms3rd
https://www.rsc.org/scripts/360.js76ms73ms1ms3rd
C
JS Bundles
Action
20 scripts, 248 KB unused
REVIEW
20 scripts, 248 KB unused
Warning::
https://www.googletagmanager.com/gtm.js?id=GTM-NWX...: 78 KB unused (46%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://cdn-ukwest.onetrust.com/scripttemplates/20...: 73 KB unused (62%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.rsc.org/scripts/751.js: 54 KB unused (79%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://ajax.googleapis.com/ajax/libs/jquery/3.7.1...: 23 KB unused (76%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.rsc.org/scripts/main.js: 21 KB unused (76%)
Consider code splitting or tree shaking to reduce unused code.
Info::
Total unused JavaScript: 248 KB
248 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://www.googletagmanager.com/gtm.js?id=GTM-NWXSBHNW169 KB78 KB (46%)✓3rd
https://cdn-ukwest.onetrust.com/scripttemplates/202505.2.0/otBannerSdk.js119 KB73 KB (62%)✓3rd
https://www.rsc.org/scripts/751.js69 KB54 KB (79%)✓3rd
https://ajax.googleapis.com/ajax/libs/jquery/3.7.1/jquery.min.js30 KB23 KB (76%)✓3rd
https://www.rsc.org/scripts/main.js28 KB21 KB (76%)✓3rd
https://www.rsc.org/scripts/551.js2 KB—✓3rd
https://cdn.jotfor.ms/s/umd/latest/for-form-embed-handler.js3 KB—✓3rd
https://cdn-ukwest.onetrust.com/scripttemplates/otSDKStub.js?did=38a172b7-f102-419f-a469-99bfedc55eec9 KB—✓3rd
https://cdn-ukwest.onetrust.com/consent/38a172b7-f102-419f-a469-99bfedc55eec/38a172b7-f102-419f-a469-99bfedc55eec.json2 KB—✓3rd
https://www.rsc.org/scripts/692.js30 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

B
Page Weight Inventory
45 resources · 1.0 MB · 248 KB savings available
REVIEW
45 resources · 1.0 MB · 248 KB savings available
Warning::
Page weight 38 KB over 1MB target
Got: 1.0 MB Expected: ≤ 1 MB
Info::
~248 KB of savings available
Warning::
44 third-party resources (100% of weight)
45 resources · 1.0 MiB · 44 third-party 37.6 KiB over 1MB target
JavaScript 50% · 531.2 KiB
Image 37% · 395.6 KiB
Font 7% · 70.1 KiB
CSS 4% · 41.4 KiB
Document 2% · 19.2 KiB
Other 0% · 4.3 KiB

~248.3 KiB of savings available

Remove unused JavaScript: 248.3 KiB
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 (70 KB)
PASS
2 fonts (70 KB)
Info::
2 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

2

70 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 1.0 s 2.0 s 3.0 s 4.0 s 5.0 s 6.0 s 7.0 s FCP 4.0 s LCP 7.5 shttps://fonts.gstatic.com/s/roboto/v51/KFO7CnqEu92Fr1ME7kSn66aGLdTylUAMa3yUBHMdazQ.woff2KFO7CnqEu92Fr1ME7kSn66a... https://fonts.gstatic.com/s/roboto/v51/KFO7CnqEu92Fr1ME7kSn66aGLdTylUAMa3yUBHMdazQ.woff2 — 36.7 KiB — 36 ms — font-display: swaphttps://fonts.gstatic.com/s/bitter/v40/rax8HiqOu8IVPmn7f4xpLjpSmw.woff2rax8HiqOu8IVPmn7f4xpLjp... https://fonts.gstatic.com/s/bitter/v40/rax8HiqOu8IVPmn7f4xpLjpSmw.woff2 — 33.4 KiB — 30 ms — font-display: swap
KFO7CnqEu92Fr1ME7kSn66a... woff2 swap
Size 37 KB
Load time 36 ms
Start 423 ms
Risk FOUT — text flashes from fallback to web font
rax8HiqOu8IVPmn7f4xpLjp... woff2 swap
Size 33 KB
Load time 30 ms
Start 892 ms
Risk FOUT — text flashes from fallback to web font
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
2 hints, 0 missing preconnects
PASS
2 hints, 0 missing preconnects
Info::
Page uses 2 resource hint(s)

Current Resource Hints

preconnect
2
preload
—
dns-prefetch
—
prefetch
—

2 resource hints configured

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
A+
Green Hosting
Whether the site is served from green-energy infrastructure
PASS

Green Hosting

This site is hosted on green energy infrastructure

Provider: Tessellate OS

Network Waterfall
45 requests over 1129ms
INFO
0 ms 1.0 s 2.0 s 3.0 s 4.0 s 5.0 s 6.0 s 7.0 s FCP 4.0 s LCP 7.5 shttps://rsc.org// https://rsc.org/ — 301 — 140 B — 110 ms — h2https://www.rsc.org/www.rsc.org/ https://www.rsc.org/ — 200 — 19.0 KiB — 218 ms — h2https://fonts.googleapis.com/css2?family=Roboto:ital,wght@0,400;0,700;1,400;1,700&family=Bitter:ital,wght@0,400;0,700;1,400;1,700&display=swapfonts.googleapis.com/css2?family=Ro... https://fonts.googleapis.com/css2?family=Roboto:ital,wght@0,400;0,700;1,400;1,700&family=Bitter:ital,wght@0,400;0,700;1,400;1,700&display=swap — 200 — 2.5 KiB — 85 ms — h2https://www.rsc.org/styles/main.csswww.rsc.org/styles/main.css https://www.rsc.org/styles/main.css — 200 — 32.0 KiB — 45 ms — h2https://www.rsc.org/_content/Kentico.Content.Web.Rcl/Content/Bundles/Public/systemPageComponents.min.csswww.rsc.org/_content/Kentico.Conten... https://www.rsc.org/_content/Kentico.Content.Web.Rcl/Content/Bundles/Public/systemPageComponents.min.css — 200 — 2.4 KiB — 70 ms — h2https://ajax.googleapis.com/ajax/libs/jquery/3.7.1/jquery.min.jsajax.googleapis.com/ajax/libs/jquer... https://ajax.googleapis.com/ajax/libs/jquery/3.7.1/jquery.min.js — 200 — 30.4 KiB — 102 ms — h2https://form.jotform.com/static/feedback2.jsform.jotform.com/static/feedback2.j... https://form.jotform.com/static/feedback2.js — 200 — 6.7 KiB — 108 ms — h2https://cdn.jotfor.ms/s/umd/latest/for-form-embed-handler.jscdn.jotfor.ms/s/umd/latest/for-form... https://cdn.jotfor.ms/s/umd/latest/for-form-embed-handler.js — 200 — 3.4 KiB — 543 ms — h2https://www.rsc.org/getContentAsset/2a7615fb-391d-41a7-948f-86adffa30852/ce180e11-21c8-44f3-8a12-93a7330b580f/rsc_logo.svg?language=enwww.rsc.org/getContentAsset/2a7615f... https://www.rsc.org/getContentAsset/2a7615fb-391d-41a7-948f-86adffa30852/ce180e11-21c8-44f3-8a12-93a7330b580f/rsc_logo.svg?language=en — 200 — 4.6 KiB — 68 ms — h2https://www.rsc.org/getContentAsset/9ba1e59e-10cd-404b-a33f-fcdfe8a721a8/97c19dfb-06fc-4638-b657-b9d8300eab48/Getty-human-hands-using-laptop.jpg?language=enwww.rsc.org/getContentAsset/9ba1e59... https://www.rsc.org/getContentAsset/9ba1e59e-10cd-404b-a33f-fcdfe8a721a8/97c19dfb-06fc-4638-b657-b9d8300eab48/Getty-human-hands-using-laptop.jpg?language=en — 200 — 74.3 KiB — 91 ms — h2https://www.rsc.org/getContentAsset/35ba565b-ab09-44e3-8cef-6f9200e86a96/97c19dfb-06fc-4638-b657-b9d8300eab48/Prizes-12-11-25.jpg?language=en&width=1460&resizemode=force&format=webpwww.rsc.org/getContentAsset/35ba565... https://www.rsc.org/getContentAsset/35ba565b-ab09-44e3-8cef-6f9200e86a96/97c19dfb-06fc-4638-b657-b9d8300eab48/Prizes-12-11-25.jpg?language=en&width=1460&resizemode=force&format=webp — 200 — 99.5 KiB — 64 ms — h2https://www.rsc.org/getContentAsset/5036fd15-7ba9-419a-a0ca-a32b4205f47e/97c19dfb-06fc-4638-b657-b9d8300eab48/publishing-journals-covers-signpost-mobile-landscape.webp?language=en&width=840&resizemode=force&format=webpwww.rsc.org/getContentAsset/5036fd1... https://www.rsc.org/getContentAsset/5036fd15-7ba9-419a-a0ca-a32b4205f47e/97c19dfb-06fc-4638-b657-b9d8300eab48/publishing-journals-covers-signpost-mobile-landscape.webp?language=en&width=840&resizemode=force&format=webp — 200 — 88.7 KiB — 152 ms — h2https://www.rsc.org/getContentAsset/30cf7b39-f3fa-4bbc-b978-dc6cdac4e3de/97c19dfb-06fc-4638-b657-b9d8300eab48/widest-shutterstock_2239596947-copy.jpg?language=en&width=960&resizemode=force&format=webpwww.rsc.org/getContentAsset/30cf7b3... https://www.rsc.org/getContentAsset/30cf7b39-f3fa-4bbc-b978-dc6cdac4e3de/97c19dfb-06fc-4638-b657-b9d8300eab48/widest-shutterstock_2239596947-copy.jpg?language=en&width=960&resizemode=force&format=webp — 200 — 52.3 KiB — 77 ms — h2https://www.rsc.org/img/favicons/site.webmanifestwww.rsc.org/img/favicons/site.webma... https://www.rsc.org/img/favicons/site.webmanifest — 200 — 677 B — 153 ms — h2https://www.rsc.org/scripts/runtime.jswww.rsc.org/scripts/runtime.js https://www.rsc.org/scripts/runtime.js — 200 — 2.2 KiB — 53 ms — h2https://www.rsc.org/scripts/main.jswww.rsc.org/scripts/main.js https://www.rsc.org/scripts/main.js — 200 — 27.6 KiB — 81 ms — h2https://www.rsc.org/Kentico.Resource/Activities/KenticoActivityLogger/LoggerV2.js?webPageIdentifier=ed556ad4-8885-40c8-b2b9-b2ddfdd6f007&languageName=en&logPageVisit=True&logCustomActivity=True&functionName=kxtwww.rsc.org/Kentico.Resource/Activi... https://www.rsc.org/Kentico.Resource/Activities/KenticoActivityLogger/LoggerV2.js?webPageIdentifier=ed556ad4-8885-40c8-b2b9-b2ddfdd6f007&languageName=en&logPageVisit=True&logCustomActivity=True&functionName=kxt — 200 — 1.1 KiB — 83 ms — h2https://www.rsc.org/getContentAsset/49ba6bc4-303d-4338-8930-d2f840c42794/97c19dfb-06fc-4638-b657-b9d8300eab48/pfas-image.jpg?language=enwww.rsc.org/getContentAsset/49ba6bc... https://www.rsc.org/getContentAsset/49ba6bc4-303d-4338-8930-d2f840c42794/97c19dfb-06fc-4638-b657-b9d8300eab48/pfas-image.jpg?language=en — 200 — 60.2 KiB — 153 ms — h2https://www.googletagmanager.com/gtm.js?id=GTM-NWXSBHNWwww.googletagmanager.com/gtm.js?id=... https://www.googletagmanager.com/gtm.js?id=GTM-NWXSBHNW — 200 — 169.3 KiB — 177 ms — h2https://www.rsc.org/getContentAsset/85edef95-946a-4cd3-bf99-3326847d0972/97c19dfb-06fc-4638-b657-b9d8300eab48/Election-ballot-box.jpg?language=en&width=936&resizemode=force&format=webpwww.rsc.org/getContentAsset/85edef9... https://www.rsc.org/getContentAsset/85edef95-946a-4cd3-bf99-3326847d0972/97c19dfb-06fc-4638-b657-b9d8300eab48/Election-ballot-box.jpg?language=en&width=936&resizemode=force&format=webp — 200 — 8.1 KiB — 126 ms — h2https://fonts.gstatic.com/s/roboto/v51/KFO7CnqEu92Fr1ME7kSn66aGLdTylUAMa3yUBHMdazQ.woff2fonts.gstatic.com/s/roboto/v51/KFO7... https://fonts.gstatic.com/s/roboto/v51/KFO7CnqEu92Fr1ME7kSn66aGLdTylUAMa3yUBHMdazQ.woff2 — 200 — 36.7 KiB — 36 ms — h3https://www.rsc.org/Kentico.Activities/KenticoActivityLogger/InitContactwww.rsc.org/Kentico.Activities/Kent... https://www.rsc.org/Kentico.Activities/KenticoActivityLogger/InitContact — 200 — 490 B — 85 ms — h2https://cdn-ukwest.onetrust.com/scripttemplates/otSDKStub.js?did=38a172b7-f102-419f-a469-99bfedc55eeccdn-ukwest.onetrust.com/scripttempl... https://cdn-ukwest.onetrust.com/scripttemplates/otSDKStub.js?did=38a172b7-f102-419f-a469-99bfedc55eec — 200 — 9.1 KiB — 101 ms — h2https://cdn-ukwest.onetrust.com/consent/38a172b7-f102-419f-a469-99bfedc55eec/38a172b7-f102-419f-a469-99bfedc55eec.jsoncdn-ukwest.onetrust.com/consent/38a... https://cdn-ukwest.onetrust.com/consent/38a172b7-f102-419f-a469-99bfedc55eec/38a172b7-f102-419f-a469-99bfedc55eec.json — 200 — 2.5 KiB — 85 ms — h2https://geolocation.onetrust.com/cookieconsentpub/v1/geo/locationgeolocation.onetrust.com/cookiecons... https://geolocation.onetrust.com/cookieconsentpub/v1/geo/location — 200 — 213 B — 64 ms — h2https://www.rsc.org/img/navIcon.svgwww.rsc.org/img/navIcon.svg https://www.rsc.org/img/navIcon.svg — 200 — 801 B — 34 ms — h2https://www.rsc.org/img/external-link.svgwww.rsc.org/img/external-link.svg https://www.rsc.org/img/external-link.svg — 200 — 963 B — 39 ms — h2https://www.rsc.org/img/curve.svgwww.rsc.org/img/curve.svg https://www.rsc.org/img/curve.svg — 200 — 933 B — 83 ms — h2https://www.rsc.org/img/chevron-right.svgwww.rsc.org/img/chevron-right.svg https://www.rsc.org/img/chevron-right.svg — 200 — 863 B — 81 ms — h2https://www.rsc.org/img/calendar.svgwww.rsc.org/img/calendar.svg https://www.rsc.org/img/calendar.svg — 200 — 875 B — 69 ms — h2
0 ms 1.0 s 2.0 s 3.0 s 4.0 s 5.0 s 6.0 s 7.0 s FCP 4.0 s LCP 7.5 shttps://rsc.org// https://rsc.org/ — 301 — 140 B — 110 ms — h2https://www.rsc.org/www.rsc.org/ https://www.rsc.org/ — 200 — 19.0 KiB — 218 ms — h2https://fonts.googleapis.com/css2?family=Roboto:ital,wght@0,400;0,700;1,400;1,700&family=Bitter:ital,wght@0,400;0,700;1,400;1,700&display=swapfonts.googleapis.com/css2?family=Ro... https://fonts.googleapis.com/css2?family=Roboto:ital,wght@0,400;0,700;1,400;1,700&family=Bitter:ital,wght@0,400;0,700;1,400;1,700&display=swap — 200 — 2.5 KiB — 85 ms — h2https://www.rsc.org/styles/main.csswww.rsc.org/styles/main.css https://www.rsc.org/styles/main.css — 200 — 32.0 KiB — 45 ms — h2https://www.rsc.org/_content/Kentico.Content.Web.Rcl/Content/Bundles/Public/systemPageComponents.min.csswww.rsc.org/_content/Kentico.Conten... https://www.rsc.org/_content/Kentico.Content.Web.Rcl/Content/Bundles/Public/systemPageComponents.min.css — 200 — 2.4 KiB — 70 ms — h2https://ajax.googleapis.com/ajax/libs/jquery/3.7.1/jquery.min.jsajax.googleapis.com/ajax/libs/jquer... https://ajax.googleapis.com/ajax/libs/jquery/3.7.1/jquery.min.js — 200 — 30.4 KiB — 102 ms — h2https://form.jotform.com/static/feedback2.jsform.jotform.com/static/feedback2.j... https://form.jotform.com/static/feedback2.js — 200 — 6.7 KiB — 108 ms — h2https://cdn.jotfor.ms/s/umd/latest/for-form-embed-handler.jscdn.jotfor.ms/s/umd/latest/for-form... https://cdn.jotfor.ms/s/umd/latest/for-form-embed-handler.js — 200 — 3.4 KiB — 543 ms — h2https://www.rsc.org/getContentAsset/2a7615fb-391d-41a7-948f-86adffa30852/ce180e11-21c8-44f3-8a12-93a7330b580f/rsc_logo.svg?language=enwww.rsc.org/getContentAsset/2a7615f... https://www.rsc.org/getContentAsset/2a7615fb-391d-41a7-948f-86adffa30852/ce180e11-21c8-44f3-8a12-93a7330b580f/rsc_logo.svg?language=en — 200 — 4.6 KiB — 68 ms — h2https://www.rsc.org/getContentAsset/9ba1e59e-10cd-404b-a33f-fcdfe8a721a8/97c19dfb-06fc-4638-b657-b9d8300eab48/Getty-human-hands-using-laptop.jpg?language=enwww.rsc.org/getContentAsset/9ba1e59... https://www.rsc.org/getContentAsset/9ba1e59e-10cd-404b-a33f-fcdfe8a721a8/97c19dfb-06fc-4638-b657-b9d8300eab48/Getty-human-hands-using-laptop.jpg?language=en — 200 — 74.3 KiB — 91 ms — h2https://www.rsc.org/getContentAsset/35ba565b-ab09-44e3-8cef-6f9200e86a96/97c19dfb-06fc-4638-b657-b9d8300eab48/Prizes-12-11-25.jpg?language=en&width=1460&resizemode=force&format=webpwww.rsc.org/getContentAsset/35ba565... https://www.rsc.org/getContentAsset/35ba565b-ab09-44e3-8cef-6f9200e86a96/97c19dfb-06fc-4638-b657-b9d8300eab48/Prizes-12-11-25.jpg?language=en&width=1460&resizemode=force&format=webp — 200 — 99.5 KiB — 64 ms — h2https://www.rsc.org/getContentAsset/5036fd15-7ba9-419a-a0ca-a32b4205f47e/97c19dfb-06fc-4638-b657-b9d8300eab48/publishing-journals-covers-signpost-mobile-landscape.webp?language=en&width=840&resizemode=force&format=webpwww.rsc.org/getContentAsset/5036fd1... https://www.rsc.org/getContentAsset/5036fd15-7ba9-419a-a0ca-a32b4205f47e/97c19dfb-06fc-4638-b657-b9d8300eab48/publishing-journals-covers-signpost-mobile-landscape.webp?language=en&width=840&resizemode=force&format=webp — 200 — 88.7 KiB — 152 ms — h2https://www.rsc.org/getContentAsset/30cf7b39-f3fa-4bbc-b978-dc6cdac4e3de/97c19dfb-06fc-4638-b657-b9d8300eab48/widest-shutterstock_2239596947-copy.jpg?language=en&width=960&resizemode=force&format=webpwww.rsc.org/getContentAsset/30cf7b3... https://www.rsc.org/getContentAsset/30cf7b39-f3fa-4bbc-b978-dc6cdac4e3de/97c19dfb-06fc-4638-b657-b9d8300eab48/widest-shutterstock_2239596947-copy.jpg?language=en&width=960&resizemode=force&format=webp — 200 — 52.3 KiB — 77 ms — h2https://www.rsc.org/img/favicons/site.webmanifestwww.rsc.org/img/favicons/site.webma... https://www.rsc.org/img/favicons/site.webmanifest — 200 — 677 B — 153 ms — h2https://www.rsc.org/scripts/runtime.jswww.rsc.org/scripts/runtime.js https://www.rsc.org/scripts/runtime.js — 200 — 2.2 KiB — 53 ms — h2https://www.rsc.org/scripts/main.jswww.rsc.org/scripts/main.js https://www.rsc.org/scripts/main.js — 200 — 27.6 KiB — 81 ms — h2https://www.rsc.org/Kentico.Resource/Activities/KenticoActivityLogger/LoggerV2.js?webPageIdentifier=ed556ad4-8885-40c8-b2b9-b2ddfdd6f007&languageName=en&logPageVisit=True&logCustomActivity=True&functionName=kxtwww.rsc.org/Kentico.Resource/Activi... https://www.rsc.org/Kentico.Resource/Activities/KenticoActivityLogger/LoggerV2.js?webPageIdentifier=ed556ad4-8885-40c8-b2b9-b2ddfdd6f007&languageName=en&logPageVisit=True&logCustomActivity=True&functionName=kxt — 200 — 1.1 KiB — 83 ms — h2https://www.rsc.org/getContentAsset/49ba6bc4-303d-4338-8930-d2f840c42794/97c19dfb-06fc-4638-b657-b9d8300eab48/pfas-image.jpg?language=enwww.rsc.org/getContentAsset/49ba6bc... https://www.rsc.org/getContentAsset/49ba6bc4-303d-4338-8930-d2f840c42794/97c19dfb-06fc-4638-b657-b9d8300eab48/pfas-image.jpg?language=en — 200 — 60.2 KiB — 153 ms — h2https://www.googletagmanager.com/gtm.js?id=GTM-NWXSBHNWwww.googletagmanager.com/gtm.js?id=... https://www.googletagmanager.com/gtm.js?id=GTM-NWXSBHNW — 200 — 169.3 KiB — 177 ms — h2https://www.rsc.org/getContentAsset/85edef95-946a-4cd3-bf99-3326847d0972/97c19dfb-06fc-4638-b657-b9d8300eab48/Election-ballot-box.jpg?language=en&width=936&resizemode=force&format=webpwww.rsc.org/getContentAsset/85edef9... https://www.rsc.org/getContentAsset/85edef95-946a-4cd3-bf99-3326847d0972/97c19dfb-06fc-4638-b657-b9d8300eab48/Election-ballot-box.jpg?language=en&width=936&resizemode=force&format=webp — 200 — 8.1 KiB — 126 ms — h2https://fonts.gstatic.com/s/roboto/v51/KFO7CnqEu92Fr1ME7kSn66aGLdTylUAMa3yUBHMdazQ.woff2fonts.gstatic.com/s/roboto/v51/KFO7... https://fonts.gstatic.com/s/roboto/v51/KFO7CnqEu92Fr1ME7kSn66aGLdTylUAMa3yUBHMdazQ.woff2 — 200 — 36.7 KiB — 36 ms — h3https://www.rsc.org/Kentico.Activities/KenticoActivityLogger/InitContactwww.rsc.org/Kentico.Activities/Kent... https://www.rsc.org/Kentico.Activities/KenticoActivityLogger/InitContact — 200 — 490 B — 85 ms — h2https://cdn-ukwest.onetrust.com/scripttemplates/otSDKStub.js?did=38a172b7-f102-419f-a469-99bfedc55eeccdn-ukwest.onetrust.com/scripttempl... https://cdn-ukwest.onetrust.com/scripttemplates/otSDKStub.js?did=38a172b7-f102-419f-a469-99bfedc55eec — 200 — 9.1 KiB — 101 ms — h2https://cdn-ukwest.onetrust.com/consent/38a172b7-f102-419f-a469-99bfedc55eec/38a172b7-f102-419f-a469-99bfedc55eec.jsoncdn-ukwest.onetrust.com/consent/38a... https://cdn-ukwest.onetrust.com/consent/38a172b7-f102-419f-a469-99bfedc55eec/38a172b7-f102-419f-a469-99bfedc55eec.json — 200 — 2.5 KiB — 85 ms — h2https://geolocation.onetrust.com/cookieconsentpub/v1/geo/locationgeolocation.onetrust.com/cookiecons... https://geolocation.onetrust.com/cookieconsentpub/v1/geo/location — 200 — 213 B — 64 ms — h2https://www.rsc.org/img/navIcon.svgwww.rsc.org/img/navIcon.svg https://www.rsc.org/img/navIcon.svg — 200 — 801 B — 34 ms — h2https://www.rsc.org/img/external-link.svgwww.rsc.org/img/external-link.svg https://www.rsc.org/img/external-link.svg — 200 — 963 B — 39 ms — h2https://www.rsc.org/img/curve.svgwww.rsc.org/img/curve.svg https://www.rsc.org/img/curve.svg — 200 — 933 B — 83 ms — h2https://www.rsc.org/img/chevron-right.svgwww.rsc.org/img/chevron-right.svg https://www.rsc.org/img/chevron-right.svg — 200 — 863 B — 81 ms — h2https://www.rsc.org/img/calendar.svgwww.rsc.org/img/calendar.svg https://www.rsc.org/img/calendar.svg — 200 — 875 B — 69 ms — h2https://fonts.gstatic.com/s/bitter/v40/rax8HiqOu8IVPmn7f4xpLjpSmw.woff2fonts.gstatic.com/s/bitter/v40/rax8... https://fonts.gstatic.com/s/bitter/v40/rax8HiqOu8IVPmn7f4xpLjpSmw.woff2 — 200 — 33.4 KiB — 30 ms — h3https://www.rsc.org/scripts/692.jswww.rsc.org/scripts/692.js https://www.rsc.org/scripts/692.js — 200 — 30.4 KiB — 62 ms — h2https://www.rsc.org/scripts/551.jswww.rsc.org/scripts/551.js https://www.rsc.org/scripts/551.js — 200 — 2.0 KiB — 83 ms — h2https://www.rsc.org/scripts/458.jswww.rsc.org/scripts/458.js https://www.rsc.org/scripts/458.js — 200 — 20.3 KiB — 79 ms — h2https://www.rsc.org/scripts/751.jswww.rsc.org/scripts/751.js https://www.rsc.org/scripts/751.js — 200 — 68.7 KiB — 89 ms — h2https://www.rsc.org/scripts/360.jswww.rsc.org/scripts/360.js https://www.rsc.org/scripts/360.js — 200 — 3.5 KiB — 97 ms — h2https://www.rsc.org/scripts/535.jswww.rsc.org/scripts/535.js https://www.rsc.org/scripts/535.js — 200 — 1.7 KiB — 108 ms — h2https://www.rsc.org/scripts/318.jswww.rsc.org/scripts/318.js https://www.rsc.org/scripts/318.js — 200 — 3.2 KiB — 116 ms — h2https://www.rsc.org/scripts/176.jswww.rsc.org/scripts/176.js https://www.rsc.org/scripts/176.js — 200 — 1.7 KiB — 127 ms — h2https://www.rsc.org/scripts/589.jswww.rsc.org/scripts/589.js https://www.rsc.org/scripts/589.js — 200 — 1.5 KiB — 140 ms — h2https://cdn-ukwest.onetrust.com/scripttemplates/202505.2.0/otBannerSdk.jscdn-ukwest.onetrust.com/scripttempl... https://cdn-ukwest.onetrust.com/scripttemplates/202505.2.0/otBannerSdk.js — 200 — 119.2 KiB — 58 ms — h2https://cdn-ukwest.onetrust.com/consent/38a172b7-f102-419f-a469-99bfedc55eec/01975deb-8273-7a6d-85ab-7137b94d0454/en.jsoncdn-ukwest.onetrust.com/consent/38a... https://cdn-ukwest.onetrust.com/consent/38a172b7-f102-419f-a469-99bfedc55eec/01975deb-8273-7a6d-85ab-7137b94d0454/en.json — 200 — 26.7 KiB — 50 ms — h2https://www.rsc.org/img/favicons/favicon.icowww.rsc.org/img/favicons/favicon.ic... https://www.rsc.org/img/favicons/favicon.ico — 200 — 3.6 KiB — 57 ms — h2https://cdn-ukwest.onetrust.com/scripttemplates/202505.2.0/assets/otCenterRounded.jsoncdn-ukwest.onetrust.com/scripttempl... https://cdn-ukwest.onetrust.com/scripttemplates/202505.2.0/assets/otCenterRounded.json — 200 — 2.9 KiB — 38 ms — h2https://cdn-ukwest.onetrust.com/scripttemplates/202505.2.0/assets/otCommonStyles.csscdn-ukwest.onetrust.com/scripttempl... https://cdn-ukwest.onetrust.com/scripttemplates/202505.2.0/assets/otCommonStyles.css — 200 — 4.5 KiB — 31 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 1163ms · 311KB · €13/mo
Unattributable
Other
Costly
Execution 380ms
Transfer 0 KB
Monthly Cost €4/mo
Google Tag Manager
Tag Manager
Costly
Execution 333ms
Transfer 169 KB
Unused 46%
Monthly Cost €4/mo
www.rsc.org
Other
Costly
Execution 238ms
Transfer 19 KB
Monthly Cost €3/mo
cdn-ukwest.onetrust.com
Other
Optional
Execution 135ms
Transfer 119 KB
Unused 62%
Monthly Cost €1/mo
www.rsc.org
Other
Optional
Execution 76ms
Transfer 4 KB
Monthly Cost €1/mo

These scripts may cost more than they're worth

  • Unattributable adds 380ms and costs ~€4/month
  • Google Tag Manager adds 333ms and costs ~€4/month
  • www.rsc.org adds 238ms 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 380ms 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 333ms 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.rsc.org takes 238ms 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 cdn-ukwest.onetrust.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.

Send Feedback