Skip to content
https://cdc.gov

Performance

· 17 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
79
GRADE
C
FIX
3
REVIEW
4
PASS
8
INFO
2

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

Mobile Desktop
63
Performance Overall performance score (0–100) based on Core Web Vitals and other metrics. 90+ is good.
91
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.
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.

1.86 s

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

13.80 s

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

211 ms

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

0.010

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

7.69 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.

14.02 s

Page Load Progression

1.3 s
2.5 s
3.8 s
5.0 s
6.3 s
7.6 s
8.8 s
10.1 s
Checks
17
8 PASS 4 REVIEW 3 FIX
F
Page Weight Budget
Action
3.0 MB transferred, 51 requests
FIX
3.0 MB transferred, 51 requests
Warning::
Page weighs 4.4 MB (3.0 MB transferred)
Warning::
Images are 2.3 MB — compress or use modern formats
Convert images to WebP/AVIF and resize to display dimensions to reduce transfer size.
Got: 2.3 MB
Info::
Fonts are 339 KB — consider subsetting or using system fonts
Subset fonts to include only used characters, or switch to system font stacks.
Got: 339 KB
Info::
51 HTTP requests
Info::
Estimated 0.63 g CO2 per page load
3.0 MB / 2.4 MB budget
3.0 MB transferred
51 requests
0.63 g CO2 per page load
Images 2.3 MiB 76%
JavaScript 342.0 KiB 11%
Fonts 339.5 KiB 11%
CSS 46.3 KiB 2%
HTML 9.8 KiB 0%
Other 6.0 KiB 0%
Other 1013 B 0%
Other 893 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

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

F
JS Execution Cost
Action
4520ms total JS execution
FIX
4520ms total JS execution
Warning::
https://cdc.gov/: 1699ms CPU time
Warning::
https://cdc.gov/TemplatePackage/5.0/js/homepage/cd...: 992ms CPU time
Warning::
Unattributable: 656ms CPU time
Warning::
https://cdc.gov/TemplatePackage/5.0/js/libs/wow.mi...: 622ms CPU time
Warning::
https://www.googletagmanager.com/gtag/js?id=G-CSLL...: 275ms CPU time
Info::
Third-party scripts: 1024ms (23% of total)

Main Thread Breakdown

Script Evaluation 39% Other 34% Style & Layout 14% Rendering 8%
ScriptTotalScriptingParse/CompileParty
https://cdc.gov/1699ms4ms3ms1st
https://cdc.gov/TemplatePackage/5.0/js/homepage/cdc-hp-2024.min.js?_=04929992ms906ms1ms1st
Unattributable656ms22ms0ms3rd
https://cdc.gov/TemplatePackage/5.0/js/libs/wow.min.js?_=04929622ms336ms1ms1st
https://www.googletagmanager.com/gtag/js?id=G-CSLL4ZEK4L275ms235ms38ms3rd
https://cdc.gov/TemplatePackage/5.0/js/app.min.js?_=04929113ms97ms11ms1st
https://www.cdc.gov/JScript/dmat/cdc-dmat.min.js?account=cdcgov&_=0887193ms78ms4ms3rd
https://cdc.gov/TemplatePackage/contrib/libs/jquery/latest/jquery.js?_=0492970ms35ms33ms1st
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
17 images, 0 KB saveable
REVIEW
17 images, 0 KB saveable
Warning::
https://cdc.gov/homepage/images/science-cdc.jpg is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://cdc.gov/TemplatePackage/5.0/img/logo/cdc-l... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://cdc.gov/homepage/images/banner/outbreak-mo... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://cdc.gov/homepage/images/banner/measles-mob... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://cdc.gov/homepage/images/banner/raw-cheese-... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://cdc.gov/TemplatePackage/5.0/img/logo/logo2... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://cdc.gov/homepage/images/Diagnosis-for-Flu.... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
17 images 2.3 MB
0 oversized -0 KB
16 legacy format
7 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

B
JS Bundles
14 scripts, 125 KB unused
REVIEW
14 scripts, 125 KB unused
Warning::
https://www.googletagmanager.com/gtag/js?id=G-CSLL...: 59 KB unused (40%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://cdc.gov/TemplatePackage/contrib/libs/jquer...: 46 KB unused (55%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://cdc.gov/TemplatePackage/contrib/libs/jquer...: unminified — 41 KB could be saved
Warning::
https://cdc.gov/TemplatePackage/5.0/js/app.min.js?...: 20 KB unused (63%)
Consider code splitting or tree shaking to reduce unused code.
Info::
Total unused JavaScript: 125 KB
125 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://www.googletagmanager.com/gtag/js?id=G-CSLL4ZEK4L147 KB59 KB (40%)✓3rd
https://cdc.gov/TemplatePackage/contrib/libs/jquery/latest/jquery.js?_=0492983 KB46 KB (55%)✗1st
https://cdc.gov/TemplatePackage/5.0/js/app.min.js?_=0492933 KB20 KB (63%)✓1st
https://cdc.gov/TemplatePackage/5.0/js/homepage/cdc-hp-2024.min.js?_=049294 KB—✓1st
https://cdc.gov/TemplatePackage/contrib/libs/bootstrap/5x/bootstrap.bundle.min.js?_=0492924 KB—✓1st
https://cdc.gov/TemplatePackage/5.0/js/libs/wow.min.js?_=049293 KB—✓1st
https://www.cdc.gov/JScript/dmat/cdc-dmat.min.js?account=cdcgov&_=0887111 KB—✓3rd
https://cdc.gov/config/cdc_config.js1 KB—✓1st
https://cdc.gov/homepage/hp2024.js1 KB—✓1st
https://www.cdc.gov/TemplatePackage/contrib/libs/dompurify/latest/purify.min.js9 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

C
Page Weight Inventory
Action
51 resources · 3.0 MB · 125 KB savings available
REVIEW
51 resources · 3.0 MB · 125 KB savings available
Warning::
Page weight 2.0 MB over 1MB target
Got: 3.0 MB Expected: ≤ 1 MB
Info::
~125 KB of savings available
Info::
11 third-party resources (6% of weight)
Info::
3 resources over 200KB
51 resources · 3.0 MiB · 11 third-party 2.0 MiB over 1MB target
Image 76% · 2.3 MiB
JavaScript 11% · 342.0 KiB
Font 11% · 339.5 KiB
CSS 2% · 46.3 KiB
Document 0% · 9.8 KiB
Other 0% · 5.9 KiB

~125.5 KiB of savings available

Remove unused JavaScript: 125.5 KiB
C
Green Hosting
Action
Whether the site is served from green-energy infrastructure
REVIEW

Green Hosting

No green hosting detected

A+
Third-Party Impact
6% third-party, 0 ms blocking
PASS
6% third-party, 0 ms blocking
Info::
Third-party code accounts for 6% of page weight (187.2 KiB of 3.0 MiB)
Info::
Third-party blocking time is low (0 ms)
94%
First-party Third-party
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
9 fonts (339 KB)
PASS
9 fonts (339 KB)
Info::
9 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

9

339 KB total

Render-blocking

0

of 9

Dominant font-display

swap

Most common across fonts

Font loading timeline
Transfer FOIT (block) FOUT (swap)
0 ms 2.0 s 4.0 s 6.0 s 8.0 s 10.0 s 12.0 s 14.0 s FCP 1.9 s LCP 13.8 shttps://cdc.gov/TemplatePackage/5.0/fonts/nunito.400.woff2nunito.400.woff2 https://cdc.gov/TemplatePackage/5.0/fonts/nunito.400.woff2 — 44.3 KiB — 306 ms — font-display: swaphttps://cdc.gov/TemplatePackage/5.0/fonts/nunito.600.woff2nunito.600.woff2 https://cdc.gov/TemplatePackage/5.0/fonts/nunito.600.woff2 — 44.6 KiB — 296 ms — font-display: swaphttps://cdc.gov/TemplatePackage/5.0/fonts/poppins.400.woff2poppins.400.woff2 https://cdc.gov/TemplatePackage/5.0/fonts/poppins.400.woff2 — 51.0 KiB — 297 ms — font-display: swaphttps://cdc.gov/TemplatePackage/5.0/fonts/cdc-fa-regular.woff2?_=28598cdc-fa-regular.woff2 https://cdc.gov/TemplatePackage/5.0/fonts/cdc-fa-regular.woff2?_=28598 — 13.6 KiB — 312 ms — font-display: swaphttps://cdc.gov/TemplatePackage/5.0/fonts/cdc-icons.woff2?_=28598cdc-icons.woff2 https://cdc.gov/TemplatePackage/5.0/fonts/cdc-icons.woff2?_=28598 — 32.4 KiB — 303 ms — font-display: swaphttps://cdc.gov/TemplatePackage/5.0/fonts/cdc-fa-light.woff2?_=28598cdc-fa-light.woff2 https://cdc.gov/TemplatePackage/5.0/fonts/cdc-fa-light.woff2?_=28598 — 14.8 KiB — 306 ms — font-display: swaphttps://cdc.gov/TemplatePackage/5.0/fonts/poppins.300.woff2poppins.300.woff2 https://cdc.gov/TemplatePackage/5.0/fonts/poppins.300.woff2 — 50.9 KiB — 313 ms — font-display: swaphttps://cdc.gov/TemplatePackage/5.0/fonts/nunito.500.woff2nunito.500.woff2 https://cdc.gov/TemplatePackage/5.0/fonts/nunito.500.woff2 — 44.4 KiB — 308 ms — font-display: swaphttps://cdc.gov/TemplatePackage/5.0/fonts/nunito.300.woff2nunito.300.woff2 https://cdc.gov/TemplatePackage/5.0/fonts/nunito.300.woff2 — 43.5 KiB — 303 ms — font-display: swap
nunito.400.woff2 woff2 swap
Size 44 KB
Load time 306 ms
Start 764 ms
Risk FOUT — text flashes from fallback to web font
nunito.600.woff2 woff2 swap
Size 45 KB
Load time 296 ms
Start 807 ms
Risk FOUT — text flashes from fallback to web font
poppins.400.woff2 woff2 swap
Size 51 KB
Load time 297 ms
Start 807 ms
Risk FOUT — text flashes from fallback to web font
cdc-fa-regular.woff2 woff2 swap
Size 14 KB
Load time 312 ms
Start 807 ms
Risk FOUT — text flashes from fallback to web font
cdc-icons.woff2 woff2 swap
Size 32 KB
Load time 303 ms
Start 807 ms
Risk FOUT — text flashes from fallback to web font
cdc-fa-light.woff2 woff2 swap
Size 15 KB
Load time 306 ms
Start 807 ms
Risk FOUT — text flashes from fallback to web font
poppins.300.woff2 woff2 swap
Size 51 KB
Load time 313 ms
Start 808 ms
Risk FOUT — text flashes from fallback to web font
nunito.500.woff2 woff2 swap
Size 44 KB
Load time 308 ms
Start 809 ms
Risk FOUT — text flashes from fallback to web font
nunito.300.woff2 woff2 swap
Size 44 KB
Load time 303 ms
Start 809 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
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
51 requests over 6599ms
INFO
0 ms 2.0 s 4.0 s 6.0 s 8.0 s 10.0 s 12.0 s 14.0 s FCP 1.9 s LCP 13.8 shttps://cdc.gov// https://cdc.gov/ — 200 — 9.8 KiB — 427 ms — h2https://cdc.gov/TemplatePackage/5.0/css/homepage/hp-2024.min.css?_=04929/TemplatePackage/5.0/css/homepage/h... https://cdc.gov/TemplatePackage/5.0/css/homepage/hp-2024.min.css?_=04929 — 200 — 43.2 KiB — 295 ms — h2https://www.cdc.gov/JScript/dmat/cdc-dmat.min.js?account=cdcgov&_=08871www.cdc.gov/JScript/dmat/cdc-dmat.m... https://www.cdc.gov/JScript/dmat/cdc-dmat.min.js?account=cdcgov&_=08871 — 200 — 11.4 KiB — 31 ms — h2https://cdc.gov/homepage/hp2024.css/homepage/hp2024.css https://cdc.gov/homepage/hp2024.css — 200 — 1.2 KiB — 303 ms — h2https://cdc.gov/TemplatePackage/5.0/js/modules/banner.js?20260409/TemplatePackage/5.0/js/modules/ban... https://cdc.gov/TemplatePackage/5.0/js/modules/banner.js?20260409 — 200 — 2.9 KiB — 304 ms — h2https://cdc.gov/TemplatePackage/5.0/img/uswds/icon-dot-gov.svg/TemplatePackage/5.0/img/uswds/icon... https://cdc.gov/TemplatePackage/5.0/img/uswds/icon-dot-gov.svg — 200 — 756 B — 106 ms — h2https://cdc.gov/TemplatePackage/5.0/img/uswds/icon-https.svg/TemplatePackage/5.0/img/uswds/icon... https://cdc.gov/TemplatePackage/5.0/img/uswds/icon-https.svg — 200 — 703 B — 295 ms — h2https://cdc.gov/TemplatePackage/5.0/img/logo/logo2.svg/TemplatePackage/5.0/img/logo/logo2... https://cdc.gov/TemplatePackage/5.0/img/logo/logo2.svg — 200 — 1.6 KiB — 104 ms — h2https://cdc.gov/TemplatePackage/5.0/img/logo/cdc-logo-tag-right.svg/TemplatePackage/5.0/img/logo/cdc-l... https://cdc.gov/TemplatePackage/5.0/img/logo/cdc-logo-tag-right.svg — 200 — 5.0 KiB — 111 ms — h2https://cdc.gov/homepage/images/Diagnosis-for-Flu.jpg/homepage/images/Diagnosis-for-Flu.... https://cdc.gov/homepage/images/Diagnosis-for-Flu.jpg — 200 — 194.4 KiB — 111 ms — h2https://cdc.gov/config/cdc_config.js/config/cdc_config.js https://cdc.gov/config/cdc_config.js — 200 — 528 B — 307 ms — h2https://cdc.gov/TemplatePackage/contrib/libs/bootstrap/5x/bootstrap.bundle.min.js?_=04929/TemplatePackage/contrib/libs/boots... https://cdc.gov/TemplatePackage/contrib/libs/bootstrap/5x/bootstrap.bundle.min.js?_=04929 — 200 — 23.6 KiB — 118 ms — h2https://cdc.gov/TemplatePackage/contrib/libs/jquery/latest/jquery.js?_=04929/TemplatePackage/contrib/libs/jquer... https://cdc.gov/TemplatePackage/contrib/libs/jquery/latest/jquery.js?_=04929 — 200 — 83.5 KiB — 118 ms — h2https://cdc.gov/TemplatePackage/5.0/js/libs/wow.min.js?_=04929/TemplatePackage/5.0/js/libs/wow.mi... https://cdc.gov/TemplatePackage/5.0/js/libs/wow.min.js?_=04929 — 200 — 3.1 KiB — 108 ms — h2https://cdc.gov/TemplatePackage/5.0/js/homepage/cdc-hp-2024.min.js?_=04929/TemplatePackage/5.0/js/homepage/cd... https://cdc.gov/TemplatePackage/5.0/js/homepage/cdc-hp-2024.min.js?_=04929 — 200 — 4.3 KiB — 313 ms — h2https://cdc.gov/TemplatePackage/5.0/js/app.min.js?_=04929/TemplatePackage/5.0/js/app.min.js?... https://cdc.gov/TemplatePackage/5.0/js/app.min.js?_=04929 — 200 — 32.7 KiB — 335 ms — h2https://cdc.gov/homepage/hp2024.js/homepage/hp2024.js https://cdc.gov/homepage/hp2024.js — 200 — 940 B — 317 ms — h2https://cdc.gov/TemplatePackage/5.0/json/manifest.json/TemplatePackage/5.0/json/manifest.... https://cdc.gov/TemplatePackage/5.0/json/manifest.json — 200 — 1013 B — 358 ms — h2https://cdc.gov/TemplatePackage/5.0/img/uswds/us_flag_small.png/TemplatePackage/5.0/img/uswds/us_f... https://cdc.gov/TemplatePackage/5.0/img/uswds/us_flag_small.png — 200 — 898 B — 110 ms — h2https://cdc.gov/TemplatePackage/5.0/img/homepage/outbreak.svg/TemplatePackage/5.0/img/homepage/o... https://cdc.gov/TemplatePackage/5.0/img/homepage/outbreak.svg — 200 — 186.6 KiB — 324 ms — h2https://cdc.gov/TemplatePackage/5.0/img/homepage/aboutcdc.png/TemplatePackage/5.0/img/homepage/a... https://cdc.gov/TemplatePackage/5.0/img/homepage/aboutcdc.png — 200 — 242.8 KiB — 313 ms — h2https://cdc.gov/homepage/images/banner/raw-cheese-4-mobile.jpg/homepage/images/banner/raw-cheese-... https://cdc.gov/homepage/images/banner/raw-cheese-4-mobile.jpg — 200 — 103.3 KiB — 313 ms — h2https://cdc.gov/homepage/images/banner/measles-mobile_2.jpg/homepage/images/banner/measles-mob... https://cdc.gov/homepage/images/banner/measles-mobile_2.jpg — 200 — 142.7 KiB — 367 ms — h2https://cdc.gov/homepage/images/banner/outbreak-mobile.jpg/homepage/images/banner/outbreak-mo... https://cdc.gov/homepage/images/banner/outbreak-mobile.jpg — 200 — 131.5 KiB — 290 ms — h2https://cdc.gov/TemplatePackage/5.0/img/homepage/mmwr.png/TemplatePackage/5.0/img/homepage/m... https://cdc.gov/TemplatePackage/5.0/img/homepage/mmwr.png — 200 — 46.2 KiB — 334 ms — h2https://cdc.gov/TemplatePackage/5.0/img/homepage/eid.png/TemplatePackage/5.0/img/homepage/e... https://cdc.gov/TemplatePackage/5.0/img/homepage/eid.png — 200 — 35.6 KiB — 317 ms — h2https://cdc.gov/TemplatePackage/5.0/img/homepage/pcd.png/TemplatePackage/5.0/img/homepage/p... https://cdc.gov/TemplatePackage/5.0/img/homepage/pcd.png — 200 — 49.1 KiB — 306 ms — h2https://cdc.gov/homepage/images/science-cdc.jpg/homepage/images/science-cdc.jpg https://cdc.gov/homepage/images/science-cdc.jpg — 200 — 336.4 KiB — 301 ms — h2https://cdc.gov/TemplatePackage/5.0/css/print.min.css?_=04929/TemplatePackage/5.0/css/print.min.... https://cdc.gov/TemplatePackage/5.0/css/print.min.css?_=04929 — 200 — 1.9 KiB — 318 ms — h2https://cdc.gov/TemplatePackage/5.0/fonts/nunito.400.woff2/TemplatePackage/5.0/fonts/nunito.4... https://cdc.gov/TemplatePackage/5.0/fonts/nunito.400.woff2 — 200 — 44.3 KiB — 306 ms — h2
0 ms 2.0 s 4.0 s 6.0 s 8.0 s 10.0 s 12.0 s 14.0 s FCP 1.9 s LCP 13.8 shttps://cdc.gov// https://cdc.gov/ — 200 — 9.8 KiB — 427 ms — h2https://cdc.gov/TemplatePackage/5.0/css/homepage/hp-2024.min.css?_=04929/TemplatePackage/5.0/css/homepage/h... https://cdc.gov/TemplatePackage/5.0/css/homepage/hp-2024.min.css?_=04929 — 200 — 43.2 KiB — 295 ms — h2https://www.cdc.gov/JScript/dmat/cdc-dmat.min.js?account=cdcgov&_=08871www.cdc.gov/JScript/dmat/cdc-dmat.m... https://www.cdc.gov/JScript/dmat/cdc-dmat.min.js?account=cdcgov&_=08871 — 200 — 11.4 KiB — 31 ms — h2https://cdc.gov/homepage/hp2024.css/homepage/hp2024.css https://cdc.gov/homepage/hp2024.css — 200 — 1.2 KiB — 303 ms — h2https://cdc.gov/TemplatePackage/5.0/js/modules/banner.js?20260409/TemplatePackage/5.0/js/modules/ban... https://cdc.gov/TemplatePackage/5.0/js/modules/banner.js?20260409 — 200 — 2.9 KiB — 304 ms — h2https://cdc.gov/TemplatePackage/5.0/img/uswds/icon-dot-gov.svg/TemplatePackage/5.0/img/uswds/icon... https://cdc.gov/TemplatePackage/5.0/img/uswds/icon-dot-gov.svg — 200 — 756 B — 106 ms — h2https://cdc.gov/TemplatePackage/5.0/img/uswds/icon-https.svg/TemplatePackage/5.0/img/uswds/icon... https://cdc.gov/TemplatePackage/5.0/img/uswds/icon-https.svg — 200 — 703 B — 295 ms — h2https://cdc.gov/TemplatePackage/5.0/img/logo/logo2.svg/TemplatePackage/5.0/img/logo/logo2... https://cdc.gov/TemplatePackage/5.0/img/logo/logo2.svg — 200 — 1.6 KiB — 104 ms — h2https://cdc.gov/TemplatePackage/5.0/img/logo/cdc-logo-tag-right.svg/TemplatePackage/5.0/img/logo/cdc-l... https://cdc.gov/TemplatePackage/5.0/img/logo/cdc-logo-tag-right.svg — 200 — 5.0 KiB — 111 ms — h2https://cdc.gov/homepage/images/Diagnosis-for-Flu.jpg/homepage/images/Diagnosis-for-Flu.... https://cdc.gov/homepage/images/Diagnosis-for-Flu.jpg — 200 — 194.4 KiB — 111 ms — h2https://cdc.gov/config/cdc_config.js/config/cdc_config.js https://cdc.gov/config/cdc_config.js — 200 — 528 B — 307 ms — h2https://cdc.gov/TemplatePackage/contrib/libs/bootstrap/5x/bootstrap.bundle.min.js?_=04929/TemplatePackage/contrib/libs/boots... https://cdc.gov/TemplatePackage/contrib/libs/bootstrap/5x/bootstrap.bundle.min.js?_=04929 — 200 — 23.6 KiB — 118 ms — h2https://cdc.gov/TemplatePackage/contrib/libs/jquery/latest/jquery.js?_=04929/TemplatePackage/contrib/libs/jquer... https://cdc.gov/TemplatePackage/contrib/libs/jquery/latest/jquery.js?_=04929 — 200 — 83.5 KiB — 118 ms — h2https://cdc.gov/TemplatePackage/5.0/js/libs/wow.min.js?_=04929/TemplatePackage/5.0/js/libs/wow.mi... https://cdc.gov/TemplatePackage/5.0/js/libs/wow.min.js?_=04929 — 200 — 3.1 KiB — 108 ms — h2https://cdc.gov/TemplatePackage/5.0/js/homepage/cdc-hp-2024.min.js?_=04929/TemplatePackage/5.0/js/homepage/cd... https://cdc.gov/TemplatePackage/5.0/js/homepage/cdc-hp-2024.min.js?_=04929 — 200 — 4.3 KiB — 313 ms — h2https://cdc.gov/TemplatePackage/5.0/js/app.min.js?_=04929/TemplatePackage/5.0/js/app.min.js?... https://cdc.gov/TemplatePackage/5.0/js/app.min.js?_=04929 — 200 — 32.7 KiB — 335 ms — h2https://cdc.gov/homepage/hp2024.js/homepage/hp2024.js https://cdc.gov/homepage/hp2024.js — 200 — 940 B — 317 ms — h2https://cdc.gov/TemplatePackage/5.0/json/manifest.json/TemplatePackage/5.0/json/manifest.... https://cdc.gov/TemplatePackage/5.0/json/manifest.json — 200 — 1013 B — 358 ms — h2https://cdc.gov/TemplatePackage/5.0/img/uswds/us_flag_small.png/TemplatePackage/5.0/img/uswds/us_f... https://cdc.gov/TemplatePackage/5.0/img/uswds/us_flag_small.png — 200 — 898 B — 110 ms — h2https://cdc.gov/TemplatePackage/5.0/img/homepage/outbreak.svg/TemplatePackage/5.0/img/homepage/o... https://cdc.gov/TemplatePackage/5.0/img/homepage/outbreak.svg — 200 — 186.6 KiB — 324 ms — h2https://cdc.gov/TemplatePackage/5.0/img/homepage/aboutcdc.png/TemplatePackage/5.0/img/homepage/a... https://cdc.gov/TemplatePackage/5.0/img/homepage/aboutcdc.png — 200 — 242.8 KiB — 313 ms — h2https://cdc.gov/homepage/images/banner/raw-cheese-4-mobile.jpg/homepage/images/banner/raw-cheese-... https://cdc.gov/homepage/images/banner/raw-cheese-4-mobile.jpg — 200 — 103.3 KiB — 313 ms — h2https://cdc.gov/homepage/images/banner/measles-mobile_2.jpg/homepage/images/banner/measles-mob... https://cdc.gov/homepage/images/banner/measles-mobile_2.jpg — 200 — 142.7 KiB — 367 ms — h2https://cdc.gov/homepage/images/banner/outbreak-mobile.jpg/homepage/images/banner/outbreak-mo... https://cdc.gov/homepage/images/banner/outbreak-mobile.jpg — 200 — 131.5 KiB — 290 ms — h2https://cdc.gov/TemplatePackage/5.0/img/homepage/mmwr.png/TemplatePackage/5.0/img/homepage/m... https://cdc.gov/TemplatePackage/5.0/img/homepage/mmwr.png — 200 — 46.2 KiB — 334 ms — h2https://cdc.gov/TemplatePackage/5.0/img/homepage/eid.png/TemplatePackage/5.0/img/homepage/e... https://cdc.gov/TemplatePackage/5.0/img/homepage/eid.png — 200 — 35.6 KiB — 317 ms — h2https://cdc.gov/TemplatePackage/5.0/img/homepage/pcd.png/TemplatePackage/5.0/img/homepage/p... https://cdc.gov/TemplatePackage/5.0/img/homepage/pcd.png — 200 — 49.1 KiB — 306 ms — h2https://cdc.gov/homepage/images/science-cdc.jpg/homepage/images/science-cdc.jpg https://cdc.gov/homepage/images/science-cdc.jpg — 200 — 336.4 KiB — 301 ms — h2https://cdc.gov/TemplatePackage/5.0/css/print.min.css?_=04929/TemplatePackage/5.0/css/print.min.... https://cdc.gov/TemplatePackage/5.0/css/print.min.css?_=04929 — 200 — 1.9 KiB — 318 ms — h2https://cdc.gov/TemplatePackage/5.0/fonts/nunito.400.woff2/TemplatePackage/5.0/fonts/nunito.4... https://cdc.gov/TemplatePackage/5.0/fonts/nunito.400.woff2 — 200 — 44.3 KiB — 306 ms — h2https://cdc.gov/TemplatePackage/5.0/img/homepage/background-swirl.svg/TemplatePackage/5.0/img/homepage/b... https://cdc.gov/TemplatePackage/5.0/img/homepage/background-swirl.svg — 200 — 845.9 KiB — 317 ms — h2https://cdc.gov/TemplatePackage/5.0/fonts/nunito.600.woff2/TemplatePackage/5.0/fonts/nunito.6... https://cdc.gov/TemplatePackage/5.0/fonts/nunito.600.woff2 — 200 — 44.6 KiB — 296 ms — h2https://cdc.gov/TemplatePackage/5.0/fonts/poppins.400.woff2/TemplatePackage/5.0/fonts/poppins.... https://cdc.gov/TemplatePackage/5.0/fonts/poppins.400.woff2 — 200 — 51.0 KiB — 297 ms — h2https://cdc.gov/TemplatePackage/5.0/fonts/cdc-fa-regular.woff2?_=28598/TemplatePackage/5.0/fonts/cdc-fa-r... https://cdc.gov/TemplatePackage/5.0/fonts/cdc-fa-regular.woff2?_=28598 — 200 — 13.6 KiB — 312 ms — h2https://cdc.gov/TemplatePackage/5.0/fonts/cdc-icons.woff2?_=28598/TemplatePackage/5.0/fonts/cdc-icon... https://cdc.gov/TemplatePackage/5.0/fonts/cdc-icons.woff2?_=28598 — 200 — 32.4 KiB — 303 ms — h2https://cdc.gov/TemplatePackage/5.0/fonts/cdc-fa-light.woff2?_=28598/TemplatePackage/5.0/fonts/cdc-fa-l... https://cdc.gov/TemplatePackage/5.0/fonts/cdc-fa-light.woff2?_=28598 — 200 — 14.8 KiB — 306 ms — h2https://cdc.gov/TemplatePackage/5.0/fonts/poppins.300.woff2/TemplatePackage/5.0/fonts/poppins.... https://cdc.gov/TemplatePackage/5.0/fonts/poppins.300.woff2 — 200 — 50.9 KiB — 313 ms — h2https://cdc.gov/TemplatePackage/5.0/fonts/nunito.500.woff2/TemplatePackage/5.0/fonts/nunito.5... https://cdc.gov/TemplatePackage/5.0/fonts/nunito.500.woff2 — 200 — 44.4 KiB — 308 ms — h2https://cdc.gov/TemplatePackage/5.0/fonts/nunito.300.woff2/TemplatePackage/5.0/fonts/nunito.3... https://cdc.gov/TemplatePackage/5.0/fonts/nunito.300.woff2 — 200 — 43.5 KiB — 303 ms — h2https://www.cdc.gov/TemplatePackage/contrib/libs/dompurify/latest/purify.min.jswww.cdc.gov/TemplatePackage/contrib... https://www.cdc.gov/TemplatePackage/contrib/libs/dompurify/latest/purify.min.js — 200 — 8.8 KiB — 37 ms — h2https://mtrics.cdc.gov/cdcgov/1.0.0/cdc.png?_=s17763602837510000&ms=1&dt=2026-04-16T17%3A24%3A43.747Z&u=https%3A%2F%2Fcdc.gov%2F&r=&v=1.0.1&cvid=ca73f56b-d377-497e-b42b-c8e91ae55544&csid=96ef69c9-9246-4af5-ae1b-a290b6510ffb&arid=b425110260282df95a3Z&avid=b425110260282df95a3Z&vis_pnum=1&ch=CDC&pn=Centers%20for%20Disease%20Control%20and%20Prevention%20%7C%20CDC&sr=412x823&dpr=1.75&so=0&c=24&w=412&h=823&l=eng&k=Y&pk=Y&evt=0&p8=Web%20Page&p49=none&p66=DFE&e56=1&me=1mtrics.cdc.gov/cdcgov/1.0.0/cdc.png... https://mtrics.cdc.gov/cdcgov/1.0.0/cdc.png?_=s17763602837510000&ms=1&dt=2026-04-16T17%3A24%3A43.747Z&u=https%3A%2F%2Fcdc.gov%2F&r=&v=1.0.1&cvid=ca73f56b-d377-497e-b42b-c8e91ae55544&csid=96ef69c9-9246-4af5-ae1b-a290b6510ffb&arid=b425110260282df95a3Z&avid=b425110260282df95a3Z&vis_pnum=1&ch=CDC&pn=Centers%20for%20Disease%20Control%20and%20Prevention%20%7C%20CDC&sr=412x823&dpr=1.75&so=0&c=24&w=412&h=823&l=eng&k=Y&pk=Y&evt=0&p8=Web%20Page&p49=none&p66=DFE&e56=1&me=1 — 200 — 598 B — 206 ms — h2https://www.cdc.gov/JScript/metrics/google/Universal-Federated-Analytics-Min.js?agency=HHS&amp;subagency=CDCwww.cdc.gov/JScript/metrics/google/... https://www.cdc.gov/JScript/metrics/google/Universal-Federated-Analytics-Min.js?agency=HHS&amp;subagency=CDC — 200 — 9.1 KiB — 19 ms — h2https://mtrics.cdc.gov/cdcgov/1.0.0/cdc.png?_=s17763602837560000&ms=1&dt=2026-04-16T17%3A24%3A43.747Z&u=https%3A%2F%2Fcdc.gov%2F&r=&v=1.0.1&cvid=ca73f56b-d377-497e-b42b-c8e91ae55544&csid=96ef69c9-9246-4af5-ae1b-a290b6510ffb&arid=b425110260282df95a3Z&avid=b425110260282df95a3Z&ch=CDC&pn=Centers%20for%20Disease%20Control%20and%20Prevention%20%7C%20CDC&sr=412x823&dpr=1.75&so=0&c=24&w=412&h=823&l=eng&k=Y&pk=Y&evt=2&event=Start&et=0&sd=0.0&to=0&to2=0&dh=4225&vph=823&me=1mtrics.cdc.gov/cdcgov/1.0.0/cdc.png... https://mtrics.cdc.gov/cdcgov/1.0.0/cdc.png?_=s17763602837560000&ms=1&dt=2026-04-16T17%3A24%3A43.747Z&u=https%3A%2F%2Fcdc.gov%2F&r=&v=1.0.1&cvid=ca73f56b-d377-497e-b42b-c8e91ae55544&csid=96ef69c9-9246-4af5-ae1b-a290b6510ffb&arid=b425110260282df95a3Z&avid=b425110260282df95a3Z&ch=CDC&pn=Centers%20for%20Disease%20Control%20and%20Prevention%20%7C%20CDC&sr=412x823&dpr=1.75&so=0&c=24&w=412&h=823&l=eng&k=Y&pk=Y&evt=2&event=Start&et=0&sd=0.0&to=0&to2=0&dh=4225&vph=823&me=1 — 200 — 599 B — 434 ms — h2https://www.cdc.gov/config/banner.txt?v2www.cdc.gov/config/banner.txt?v2 https://www.cdc.gov/config/banner.txt?v2 — 200 — 4.3 KiB — 20 ms — h2https://dap.digitalgov.gov/web-vitals/dist/web-vitals.attribution.iife.jsdap.digitalgov.gov/web-vitals/dist/... https://dap.digitalgov.gov/web-vitals/dist/web-vitals.attribution.iife.js — 200 — 4.5 KiB — 83 ms — h3https://www.googletagmanager.com/gtag/js?id=G-CSLL4ZEK4Lwww.googletagmanager.com/gtag/js?id... https://www.googletagmanager.com/gtag/js?id=G-CSLL4ZEK4L — 200 — 147.4 KiB — 274 ms — h2https://region1.google-analytics.com/g/collect?v=2&tid=G-CSLL4ZEK4L&gtm=45je64f0v9131934939za200zd9131934939&_p=1776360283797&gcd=13l3lPl2l1l1&npa=1&dma_cps=a&dma=1&are=1&cid=1251243627.1776360284&frm=0&pscdl=noapi&rcb=8&sr=412x823&uaa=&uab=64&uafvl=Chromium%3B147.0.7727.55%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=0~115616985~115938466~115938468~116363098~117266401~118131810&dl=https%3A%2F%2Fcdc.gov%2F&dt=Centers%20for%20Disease%20Control%20and%20Prevention%20%7C%20CDC&dr=&sid=1776360284&sct=1&seg=0&_tu=wA&en=page_view&_fv=1&_nsi=1&_ss=1&_ee=1&ep.agency=HHS&ep.subagency=CDC.GOV&ep.site_topic=unspecified%3Acdc.gov&ep.site_platform=unspecified%3Acdc.gov&ep.script_source=https%3A%2F%2Fcdc.gov%2Fjscript%2Fmetrics%2Fgoogle%2Funiversal-federated-analytics-min.js&ep.version=20250212%20v8.6%20-%20ga4&ep.protocol=https%3A&ep.using_parallel_tracker=no&ep.hostname_dimension=cdc.gov&tfd=1551region1.google-analytics.com/g/coll... https://region1.google-analytics.com/g/collect?v=2&tid=G-CSLL4ZEK4L&gtm=45je64f0v9131934939za200zd9131934939&_p=1776360283797&gcd=13l3lPl2l1l1&npa=1&dma_cps=a&dma=1&are=1&cid=1251243627.1776360284&frm=0&pscdl=noapi&rcb=8&sr=412x823&uaa=&uab=64&uafvl=Chromium%3B147.0.7727.55%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=0~115616985~115938466~115938468~116363098~117266401~118131810&dl=https%3A%2F%2Fcdc.gov%2F&dt=Centers%20for%20Disease%20Control%20and%20Prevention%20%7C%20CDC&dr=&sid=1776360284&sct=1&seg=0&_tu=wA&en=page_view&_fv=1&_nsi=1&_ss=1&_ee=1&ep.agency=HHS&ep.subagency=CDC.GOV&ep.site_topic=unspecified%3Acdc.gov&ep.site_platform=unspecified%3Acdc.gov&ep.script_source=https%3A%2F%2Fcdc.gov%2Fjscript%2Fmetrics%2Fgoogle%2Funiversal-federated-analytics-min.js&ep.version=20250212%20v8.6%20-%20ga4&ep.protocol=https%3A&ep.using_parallel_tracker=no&ep.hostname_dimension=cdc.gov&tfd=1551 — 204 — 543 B — 92 ms — h2https://cdc.gov/TemplatePackage/contrib/libs/qrcodejs/latest/qrcode.min.js/TemplatePackage/contrib/libs/qrcod... https://cdc.gov/TemplatePackage/contrib/libs/qrcodejs/latest/qrcode.min.js — 200 — 9.2 KiB — 105 ms — h2https://cdc.gov/TemplatePackage/5.0/img/favicon/favicon-32x32.png/TemplatePackage/5.0/img/favicon/fa... https://cdc.gov/TemplatePackage/5.0/img/favicon/favicon-32x32.png — 200 — 893 B — 104 ms — h2data:image/jpeg;base64,/9j/4AAQSkZJRgABAQAAAQABAAD/4gHYSUNDX1BST0ZJTEUAAQEAAAHIAAAAAAQwAABtbnRyUkdC…data:image/jpeg;base64,/9j/4AAQSkZJ... data:image/jpeg;base64,/9j/4AAQSkZJRgABAQAAAQABAAD/4gHYSUNDX1BST0ZJTEUAAQEAAAHIAAAAAAQwAABtbnRyUkdC… — 200 — 0 B — 0 ms — datahttps://region1.google-analytics.com/g/collect?v=2&tid=G-CSLL4ZEK4L&gtm=45je64f0v9131934939za200zd9131934939&_p=1776360283797&gcd=13l3lPl2l1l1&npa=1&dma_cps=a&dma=1&_eu=AAAAAAQ&are=1&cid=1251243627.1776360284&frm=0&pscdl=noapi&rcb=8&sr=412x823&uaa=&uab=64&uafvl=Chromium%3B147.0.7727.55%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&tag_exp=0~115616985~115938466~115938468~116363098~117266401~118131810&dl=https%3A%2F%2Fcdc.gov%2F&dt=Centers%20for%20Disease%20Control%20and%20Prevention%20%7C%20CDC&dr=&sid=1776360284&sct=1&seg=0&_tu=wA&_s=2&tfd=6560region1.google-analytics.com/g/coll... https://region1.google-analytics.com/g/collect?v=2&tid=G-CSLL4ZEK4L&gtm=45je64f0v9131934939za200zd9131934939&_p=1776360283797&gcd=13l3lPl2l1l1&npa=1&dma_cps=a&dma=1&_eu=AAAAAAQ&are=1&cid=1251243627.1776360284&frm=0&pscdl=noapi&rcb=8&sr=412x823&uaa=&uab=64&uafvl=Chromium%3B147.0.7727.55%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&tag_exp=0~115616985~115938466~115938468~116363098~117266401~118131810&dl=https%3A%2F%2Fcdc.gov%2F&dt=Centers%20for%20Disease%20Control%20and%20Prevention%20%7C%20CDC&dr=&sid=1776360284&sct=1&seg=0&_tu=wA&_s=2&tfd=6560 — 204 — 48 B — 39 ms — h2
HTML JavaScript CSS Images Fonts XHR/Fetch Other
Third-Party Script Cost
Per-script blocking time, transfer cost, and cache headers
INFO
23% of JavaScript execution is third-party
First-party Third-party 1024ms · 159KB · $14/mo
Unattributable
Other
Costly
Execution 656ms
Transfer 0 KB
Monthly Cost $9/mo
Google Tag Manager
Tag Manager
Costly
Execution 275ms
Transfer 147 KB
Unused 40%
Monthly Cost $4/mo
www.cdc.gov
Other
Optional
Execution 93ms
Transfer 11 KB
Monthly Cost $1/mo

These scripts may cost more than they're worth

  • Unattributable adds 656ms and costs ~$9/month
  • Google Tag Manager adds 275ms and costs ~$4/month

Unattributable takes 656ms 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 275ms 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

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