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Performance

· 17 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
87
GRADE
B
FIX
1
REVIEW
4
PASS
10
INFO
2

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

Mobile Desktop
62
Performance Overall performance score (0–100) based on Core Web Vitals and other metrics. 90+ is good.
88
Accessibility Measures how accessible the page is for users with disabilities. Checks color contrast, ARIA labels, and semantic HTML.
92
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.

3.11 s

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

6.35 s

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

313 ms

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

0.000

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

4.95 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.

6.41 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
10 PASS 4 REVIEW 1 FIX
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
Third-Party Impact
54% third-party, 0 ms blocking
REVIEW
54% third-party, 0 ms blocking
Warning::
Third-party code accounts for 54% of page weight (450.9 KiB of 831.0 KiB)
Info::
Third-party blocking time is low (0 ms)
46%
54%
First-party Third-party
C
Image Optimization
Action
46 images, 0 KB saveable
REVIEW
46 images, 0 KB saveable
Warning::
https://go.dev/images/logos/social/bluesky.svg is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://go.dev/images/logos/social/twitter.svg is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://go.dev/images/logos/social/slack.svg is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://go.dev/images/icons/package.svg is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://go.dev/images/logos/social/reddit.svg is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://go.dev/images/icons/code.svg is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://go.dev/images/logos/social/mastodon.svg is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://go.dev/images/icons/gear.svg is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://go.dev/images/gophers/pilot-bust.svg is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://go.dev/images/google-white.png is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://go.dev/images/logos/social/google-groups.s... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://go.dev/images/logos/social/github.svg is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://go.dev/images/logos/social/stack-overflow.... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://go.dev/images/icons/sphere.svg is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://go.dev/images/icons/command-folder.svg is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
46 images 241 KB
0 oversized -0 KB
45 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
JS Execution Cost
Action
1581ms total JS execution
REVIEW
1581ms total JS execution
Warning::
Unattributable: 570ms CPU time
Warning::
https://www.googletagmanager.com/gtm.js?id=GTM-W8M...: 467ms CPU time
Info::
https://www.googletagmanager.com/gtag/js?id=G-HL38...: 189ms CPU time
Info::
https://go.dev/js/carousels.js: 142ms CPU time
Info::
https://go.dev/: 128ms CPU time
Warning::
Third-party scripts: 1226ms (78% of total)

Main Thread Breakdown

Script Evaluation 36% Other 34% Script Parsing & Compilation 13% Style & Layout 12% Parse HTML & CSS 3%
ScriptTotalScriptingParse/CompileParty
Unattributable570ms11ms0ms3rd
https://www.googletagmanager.com/gtm.js?id=GTM-W8MVQXG467ms280ms160ms3rd
https://www.googletagmanager.com/gtag/js?id=G-HL38R6X1Q3&cx=c&gtm=4e64h1189ms147ms41ms3rd
https://go.dev/js/carousels.js142ms4ms1ms1st
https://go.dev/128ms15ms2ms1st
https://go.dev/js/index.js86ms63ms0ms1st
B
JS Bundles
13 scripts, 132 KB unused
REVIEW
13 scripts, 132 KB unused
Warning::
https://www.googletagmanager.com/gtm.js?id=GTM-W8M...: 68 KB unused (43%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.googletagmanager.com/gtag/js?id=G-HL38...: 64 KB unused (45%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://go.dev/js/playground.js: unminified — 3 KB could be saved
Info::
Total unused JavaScript: 132 KB
132 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://www.googletagmanager.com/gtm.js?id=GTM-W8MVQXG160 KB68 KB (43%)✓3rd
https://www.googletagmanager.com/gtag/js?id=G-HL38R6X1Q3&cx=c&gtm=4e64h1144 KB64 KB (45%)✓3rd
https://go.dev/js/playground.js6 KB—✗1st
https://go.dev/js/searchBox.js1 KB—✓1st
https://go.dev/js/misc.js2 KB—✓1st
https://go.dev/js/hats.js1 KB—✓1st
https://go.dev/js/site.js4 KB—✓1st
https://go.dev/js/godocs.js4 KB—✓1st
https://go.dev/js/index.js1 KB—✓1st
https://go.dev/js/copypaste.js0 KB—✓1st

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

A
Page Weight Budget
831 KB transferred, 70 requests
PASS
831 KB transferred, 70 requests
Info::
Page weighs 1.6 MB (831 KB transferred)
Info::
70 HTTP requests
Info::
Estimated 0.17 g CO2 per page load
831 KB / 2.4 MB budget
831 KB transferred
70 requests
0.17 g CO2 per page load
JavaScript 380.9 KiB 46%
Images 240.7 KiB 29%
Fonts 125.6 KiB 15%
Other 31.3 KiB 4%
CSS 27.2 KiB 3%
HTML 12.7 KiB 2%
Other 11.8 KiB 1%
Other 779 B 0%
0 2.4 MB 4.9 MB
Under budget
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
1 fonts (126 KB)
PASS
1 fonts (126 KB)
Info::
1 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

1

126 KB total

Render-blocking

0

of 1

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 FCP 3.1 s LCP 6.4 shttps://fonts.gstatic.com/s/materialicons/v145/flUhRq6tzZclQEJ-Vdg-IuiaDsNcIhQ8tQ.woff2flUhRq6tzZclQEJ-Vdg-Iui... https://fonts.gstatic.com/s/materialicons/v145/flUhRq6tzZclQEJ-Vdg-IuiaDsNcIhQ8tQ.woff2 — 125.6 KiB — 68 ms — font-display: swap
flUhRq6tzZclQEJ-Vdg-Iui... woff2 swap
Size 126 KB
Load time 68 ms
Start 703 ms
Risk FOUT — text flashes from fallback to web font
  • Subset this font — over 100 KB suggests Latin Extended or full glyph coverage that most pages don't need
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 ~63 KB and ~126 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
1 hints, 0 missing preconnects
PASS
1 hints, 0 missing preconnects
Info::
Page uses 1 resource hint(s)

Current Resource Hints

preconnect
1
preload
—
dns-prefetch
—
prefetch
—

1 resource hints configured

A
Page Weight Inventory
70 resources · 831 KB · 132 KB savings available
PASS
70 resources · 831 KB · 132 KB savings available
Info::
Within 1MB page-weight target
Got: 831 KB
Info::
~132 KB of savings available
Warning::
6 third-party resources (54% of weight)
70 resources · 831.0 KiB · 6 third-party Within 1MB page-weight target
JavaScript 46% · 380.9 KiB
Image 33% · 272.0 KiB
Font 15% · 125.6 KiB
CSS 3% · 27.2 KiB
Document 2% · 12.7 KiB
Other 2% · 12.6 KiB

~132.3 KiB of savings available

Remove unused JavaScript: 132.3 KiB
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: Google Cloud

Network Waterfall
70 requests over 2267ms
INFO
0 ms 1.0 s 2.0 s 3.0 s 4.0 s 5.0 s 6.0 s FCP 3.1 s LCP 6.4 shttps://go.dev// https://go.dev/ — 200 — 12.7 KiB — 168 ms — h2https://fonts.googleapis.com/css?family=Material+Iconsfonts.googleapis.com/css?family=Mat... https://fonts.googleapis.com/css?family=Material+Icons — 200 — 817 B — 95 ms — h2https://go.dev/css/styles.css/css/styles.css https://go.dev/css/styles.css — 200 — 26.4 KiB — 164 ms — h2https://go.dev/js/site.js/js/site.js https://go.dev/js/site.js — 200 — 3.8 KiB — 142 ms — h2https://go.dev/images/go-logo-white.svg/images/go-logo-white.svg https://go.dev/images/go-logo-white.svg — 200 — 1.5 KiB — 152 ms — h2https://go.dev/images/logos/social/google-groups.svg/images/logos/social/google-groups.... https://go.dev/images/logos/social/google-groups.svg — 200 — 1.2 KiB — 153 ms — h2https://go.dev/images/logos/social/github.svg/images/logos/social/github.svg https://go.dev/images/logos/social/github.svg — 200 — 2.5 KiB — 156 ms — h2https://go.dev/images/logos/social/bluesky.svg/images/logos/social/bluesky.svg https://go.dev/images/logos/social/bluesky.svg — 200 — 870 B — 146 ms — h2https://go.dev/images/logos/social/mastodon.svg/images/logos/social/mastodon.svg https://go.dev/images/logos/social/mastodon.svg — 200 — 2.5 KiB — 146 ms — h2https://go.dev/js/jquery.js/js/jquery.js https://go.dev/js/jquery.js — 200 — 35.6 KiB — 196 ms — h2https://go.dev/js/carousels.js/js/carousels.js https://go.dev/js/carousels.js — 200 — 1.9 KiB — 167 ms — h2https://go.dev/js/searchBox.js/js/searchBox.js https://go.dev/js/searchBox.js — 200 — 1.1 KiB — 158 ms — h2https://go.dev/js/misc.js/js/misc.js https://go.dev/js/misc.js — 200 — 1.8 KiB — 169 ms — h2https://go.dev/js/hats.js/js/hats.js https://go.dev/js/hats.js — 200 — 1.1 KiB — 386 ms — h2https://go.dev/js/playground.js/js/playground.js https://go.dev/js/playground.js — 200 — 5.9 KiB — 170 ms — h2https://go.dev/js/godocs.js/js/godocs.js https://go.dev/js/godocs.js — 200 — 4.3 KiB — 183 ms — h2https://go.dev/images/logos/social/twitter.svg/images/logos/social/twitter.svg https://go.dev/images/logos/social/twitter.svg — 200 — 2.1 KiB — 384 ms — h2https://go.dev/images/logos/social/reddit.svg/images/logos/social/reddit.svg https://go.dev/images/logos/social/reddit.svg — 200 — 1.9 KiB — 172 ms — h2https://go.dev/images/logos/social/slack.svg/images/logos/social/slack.svg https://go.dev/images/logos/social/slack.svg — 200 — 1.9 KiB — 164 ms — h2https://go.dev/images/logos/social/stack-overflow.svg/images/logos/social/stack-overflow... https://go.dev/images/logos/social/stack-overflow.svg — 200 — 720 B — 179 ms — h2https://go.dev/images/go-logo-blue.svg/images/go-logo-blue.svg https://go.dev/images/go-logo-blue.svg — 200 — 1.5 KiB — 170 ms — h2https://go.dev/images/gophers/ladder.svg/images/gophers/ladder.svg https://go.dev/images/gophers/ladder.svg — 200 — 18.3 KiB — 160 ms — h2https://go.dev/images/icons/sphere-dark.svg/images/icons/sphere-dark.svg https://go.dev/images/icons/sphere-dark.svg — 200 — 5.5 KiB — 176 ms — h2https://go.dev/images/icons/sphere.svg/images/icons/sphere.svg https://go.dev/images/icons/sphere.svg — 200 — 5.5 KiB — 161 ms — h2https://go.dev/images/icons/package.svg/images/icons/package.svg https://go.dev/images/icons/package.svg — 200 — 1.2 KiB — 173 ms — h2https://go.dev/images/icons/command-folder-dark.svg/images/icons/command-folder-dark.s... https://go.dev/images/icons/command-folder-dark.svg — 200 — 1.1 KiB — 380 ms — h2https://go.dev/images/icons/command-folder.svg/images/icons/command-folder.svg https://go.dev/images/icons/command-folder.svg — 200 — 1.1 KiB — 188 ms — h2https://go.dev/images/icons/code-dark.svg/images/icons/code-dark.svg https://go.dev/images/icons/code-dark.svg — 200 — 1.1 KiB — 182 ms — h2https://go.dev/images/icons/code.svg/images/icons/code.svg https://go.dev/images/icons/code.svg — 200 — 1.1 KiB — 176 ms — h2https://go.dev/images/icons/gear-dark.svg/images/icons/gear-dark.svg https://go.dev/images/icons/gear-dark.svg — 200 — 982 B — 185 ms — h2
0 ms 1.0 s 2.0 s 3.0 s 4.0 s 5.0 s 6.0 s FCP 3.1 s LCP 6.4 shttps://go.dev// https://go.dev/ — 200 — 12.7 KiB — 168 ms — h2https://fonts.googleapis.com/css?family=Material+Iconsfonts.googleapis.com/css?family=Mat... https://fonts.googleapis.com/css?family=Material+Icons — 200 — 817 B — 95 ms — h2https://go.dev/css/styles.css/css/styles.css https://go.dev/css/styles.css — 200 — 26.4 KiB — 164 ms — h2https://go.dev/js/site.js/js/site.js https://go.dev/js/site.js — 200 — 3.8 KiB — 142 ms — h2https://go.dev/images/go-logo-white.svg/images/go-logo-white.svg https://go.dev/images/go-logo-white.svg — 200 — 1.5 KiB — 152 ms — h2https://go.dev/images/logos/social/google-groups.svg/images/logos/social/google-groups.... https://go.dev/images/logos/social/google-groups.svg — 200 — 1.2 KiB — 153 ms — h2https://go.dev/images/logos/social/github.svg/images/logos/social/github.svg https://go.dev/images/logos/social/github.svg — 200 — 2.5 KiB — 156 ms — h2https://go.dev/images/logos/social/bluesky.svg/images/logos/social/bluesky.svg https://go.dev/images/logos/social/bluesky.svg — 200 — 870 B — 146 ms — h2https://go.dev/images/logos/social/mastodon.svg/images/logos/social/mastodon.svg https://go.dev/images/logos/social/mastodon.svg — 200 — 2.5 KiB — 146 ms — h2https://go.dev/js/jquery.js/js/jquery.js https://go.dev/js/jquery.js — 200 — 35.6 KiB — 196 ms — h2https://go.dev/js/carousels.js/js/carousels.js https://go.dev/js/carousels.js — 200 — 1.9 KiB — 167 ms — h2https://go.dev/js/searchBox.js/js/searchBox.js https://go.dev/js/searchBox.js — 200 — 1.1 KiB — 158 ms — h2https://go.dev/js/misc.js/js/misc.js https://go.dev/js/misc.js — 200 — 1.8 KiB — 169 ms — h2https://go.dev/js/hats.js/js/hats.js https://go.dev/js/hats.js — 200 — 1.1 KiB — 386 ms — h2https://go.dev/js/playground.js/js/playground.js https://go.dev/js/playground.js — 200 — 5.9 KiB — 170 ms — h2https://go.dev/js/godocs.js/js/godocs.js https://go.dev/js/godocs.js — 200 — 4.3 KiB — 183 ms — h2https://go.dev/images/logos/social/twitter.svg/images/logos/social/twitter.svg https://go.dev/images/logos/social/twitter.svg — 200 — 2.1 KiB — 384 ms — h2https://go.dev/images/logos/social/reddit.svg/images/logos/social/reddit.svg https://go.dev/images/logos/social/reddit.svg — 200 — 1.9 KiB — 172 ms — h2https://go.dev/images/logos/social/slack.svg/images/logos/social/slack.svg https://go.dev/images/logos/social/slack.svg — 200 — 1.9 KiB — 164 ms — h2https://go.dev/images/logos/social/stack-overflow.svg/images/logos/social/stack-overflow... https://go.dev/images/logos/social/stack-overflow.svg — 200 — 720 B — 179 ms — h2https://go.dev/images/go-logo-blue.svg/images/go-logo-blue.svg https://go.dev/images/go-logo-blue.svg — 200 — 1.5 KiB — 170 ms — h2https://go.dev/images/gophers/ladder.svg/images/gophers/ladder.svg https://go.dev/images/gophers/ladder.svg — 200 — 18.3 KiB — 160 ms — h2https://go.dev/images/icons/sphere-dark.svg/images/icons/sphere-dark.svg https://go.dev/images/icons/sphere-dark.svg — 200 — 5.5 KiB — 176 ms — h2https://go.dev/images/icons/sphere.svg/images/icons/sphere.svg https://go.dev/images/icons/sphere.svg — 200 — 5.5 KiB — 161 ms — h2https://go.dev/images/icons/package.svg/images/icons/package.svg https://go.dev/images/icons/package.svg — 200 — 1.2 KiB — 173 ms — h2https://go.dev/images/icons/command-folder-dark.svg/images/icons/command-folder-dark.s... https://go.dev/images/icons/command-folder-dark.svg — 200 — 1.1 KiB — 380 ms — h2https://go.dev/images/icons/command-folder.svg/images/icons/command-folder.svg https://go.dev/images/icons/command-folder.svg — 200 — 1.1 KiB — 188 ms — h2https://go.dev/images/icons/code-dark.svg/images/icons/code-dark.svg https://go.dev/images/icons/code-dark.svg — 200 — 1.1 KiB — 182 ms — h2https://go.dev/images/icons/code.svg/images/icons/code.svg https://go.dev/images/icons/code.svg — 200 — 1.1 KiB — 176 ms — h2https://go.dev/images/icons/gear-dark.svg/images/icons/gear-dark.svg https://go.dev/images/icons/gear-dark.svg — 200 — 982 B — 185 ms — h2https://go.dev/images/icons/gear.svg/images/icons/gear.svg https://go.dev/images/icons/gear.svg — 200 — 986 B — 178 ms — h2https://go.dev/js/index.js/js/index.js https://go.dev/js/index.js — 200 — 583 B — 180 ms — h2https://go.dev/images/gophers/pilot-bust.svg/images/gophers/pilot-bust.svg https://go.dev/images/gophers/pilot-bust.svg — 200 — 13.1 KiB — 185 ms — h2https://go.dev/images/icons/brightness_6_gm_grey_24dp.svg/images/icons/brightness_6_gm_grey_... https://go.dev/images/icons/brightness_6_gm_grey_24dp.svg — 200 — 393 B — 172 ms — h2https://go.dev/images/icons/brightness_2_gm_grey_24dp.svg/images/icons/brightness_2_gm_grey_... https://go.dev/images/icons/brightness_2_gm_grey_24dp.svg — 200 — 374 B — 182 ms — h2https://go.dev/images/icons/light_mode_gm_grey_24dp.svg/images/icons/light_mode_gm_grey_24... https://go.dev/images/icons/light_mode_gm_grey_24dp.svg — 200 — 1.2 KiB — 187 ms — h2https://go.dev/images/google-white.png/images/google-white.png https://go.dev/images/google-white.png — 200 — 6.3 KiB — 188 ms — h2https://go.dev/js/copypaste.js/js/copypaste.js https://go.dev/js/copypaste.js — 200 — 425 B — 168 ms — h2https://www.googletagmanager.com/gtm.js?id=GTM-W8MVQXGwww.googletagmanager.com/gtm.js?id=... https://www.googletagmanager.com/gtm.js?id=GTM-W8MVQXG — 200 — 159.8 KiB — 151 ms — h2https://www.googletagmanager.com/gtag/js?id=G-HL38R6X1Q3&cx=c&gtm=4e64h1www.googletagmanager.com/gtag/js?id... https://www.googletagmanager.com/gtag/js?id=G-HL38R6X1Q3&cx=c&gtm=4e64h1 — 200 — 143.7 KiB — 47 ms — h2https://www.google-analytics.com/analytics.jswww.google-analytics.com/analytics.... https://www.google-analytics.com/analytics.js — 200 — 20.9 KiB — 100 ms — h2https://www.google.com/ccm/collect?rcb=0&frm=0&ae=g&en=page_view&dl=https%3A%2F%2Fgo.dev%2F&scrsrc=www.googletagmanager.com&rnd=1570922607.1776802169&dt=The%20Go%20Programming%20Language&auid=1868582757.1776802169&navt=n&npa=1&ep.ads_data_redaction=0&gtm=45He64h1v830425926za200zd830425926xea&gcd=13l3l3l2l1l1&dma_cps=a&dma=1&tag_exp=0~115616986~115938465~115938469~117266401~118128922&apve=1&apvf=f&apvc=1&tft=1776802169271&tfd=665www.google.com/ccm/collect?rcb=0&fr... https://www.google.com/ccm/collect?rcb=0&frm=0&ae=g&en=page_view&dl=https%3A%2F%2Fgo.dev%2F&scrsrc=www.googletagmanager.com&rnd=1570922607.1776802169&dt=The%20Go%20Programming%20Language&auid=1868582757.1776802169&navt=n&npa=1&ep.ads_data_redaction=0&gtm=45He64h1v830425926za200zd830425926xea&gcd=13l3l3l2l1l1&dma_cps=a&dma=1&tag_exp=0~115616986~115938465~115938469~117266401~118128922&apve=1&apvf=f&apvc=1&tft=1776802169271&tfd=665 — -1 — 0 B — 82 ms — https://go.dev/images/menu-24px-white.svg/images/menu-24px-white.svg https://go.dev/images/menu-24px-white.svg — 200 — 292 B — 152 ms — h2https://fonts.gstatic.com/s/materialicons/v145/flUhRq6tzZclQEJ-Vdg-IuiaDsNcIhQ8tQ.woff2fonts.gstatic.com/s/materialicons/v... https://fonts.gstatic.com/s/materialicons/v145/flUhRq6tzZclQEJ-Vdg-IuiaDsNcIhQ8tQ.woff2 — 200 — 125.6 KiB — 68 ms — h3https://go.dev/dl/?mode=json/dl/?mode=json https://go.dev/dl/?mode=json — 200 — 5.9 KiB — 178 ms — h2https://go.dev/dl/?mode=json/dl/?mode=json https://go.dev/dl/?mode=json — 200 — 5.9 KiB — 403 ms — h2https://go.dev/doc/play/hello.go/doc/play/hello.go https://go.dev/doc/play/hello.go — 200 — 245 B — 146 ms — h2https://go.dev/images/favicon-gopher.svg/images/favicon-gopher.svg https://go.dev/images/favicon-gopher.svg — 200 — 17.5 KiB — 161 ms — h2https://go.dev/_/fmt?backend=/_/fmt?backend= https://go.dev/_/fmt?backend= — 200 — 271 B — 181 ms — h2https://go.dev/images/favicon-gopher.png/images/favicon-gopher.png https://go.dev/images/favicon-gopher.png — 200 — 13.8 KiB — 182 ms — h2https://go.dev/_/compile?backend=/_/compile?backend= https://go.dev/_/compile?backend= — 200 — 263 B — 1.1 s — h2https://go.dev/images/logos/google.svg/images/logos/google.svg https://go.dev/images/logos/google.svg — 200 — 2.3 KiB — 162 ms — h2https://go.dev/images/logos/paypal.svg/images/logos/paypal.svg https://go.dev/images/logos/paypal.svg — 200 — 1.8 KiB — 244 ms — h2https://go.dev/images/logos/american-express.svg/images/logos/american-express.svg https://go.dev/images/logos/american-express.svg — 200 — 3.5 KiB — 214 ms — h2https://go.dev/images/logos/mercadolibre_light.svg/images/logos/mercadolibre_light.sv... https://go.dev/images/logos/mercadolibre_light.svg — 200 — 12.0 KiB — 215 ms — h2https://go.dev/images/logos/bitly.svg/images/logos/bitly.svg https://go.dev/images/logos/bitly.svg — 200 — 4.0 KiB — 220 ms — h2https://go.dev/images/logos/capitalone_light.svg/images/logos/capitalone_light.svg https://go.dev/images/logos/capitalone_light.svg — 200 — 6.6 KiB — 217 ms — h2https://go.dev/images/logos/cockroach.svg/images/logos/cockroach.svg https://go.dev/images/logos/cockroach.svg — 200 — 607 B — 167 ms — h2https://go.dev/images/logos/dropbox.png/images/logos/dropbox.png https://go.dev/images/logos/dropbox.png — 200 — 3.0 KiB — 163 ms — h2https://go.dev/images/logos/cloudflare_light.svg/images/logos/cloudflare_light.svg https://go.dev/images/logos/cloudflare_light.svg — 200 — 3.4 KiB — 160 ms — h2https://go.dev/images/logos/meta_light.svg/images/logos/meta_light.svg https://go.dev/images/logos/meta_light.svg — 200 — 4.2 KiB — 167 ms — h2https://go.dev/images/logos/microsoft_light.svg/images/logos/microsoft_light.svg https://go.dev/images/logos/microsoft_light.svg — 200 — 3.9 KiB — 157 ms — h2https://go.dev/images/logos/wildlife_light.svg/images/logos/wildlife_light.svg https://go.dev/images/logos/wildlife_light.svg — 200 — 2.6 KiB — 161 ms — h2https://go.dev/images/logos/bytedance_light.svg/images/logos/bytedance_light.svg https://go.dev/images/logos/bytedance_light.svg — 200 — 4.1 KiB — 168 ms — h2https://go.dev/images/logos/netflix.svg/images/logos/netflix.svg https://go.dev/images/logos/netflix.svg — 200 — 998 B — 163 ms — h2https://go.dev/images/logos/riot_light.svg/images/logos/riot_light.svg https://go.dev/images/logos/riot_light.svg — 200 — 2.0 KiB — 164 ms — h2https://go.dev/images/logos/salesforce.svg/images/logos/salesforce.svg https://go.dev/images/logos/salesforce.svg — 200 — 6.1 KiB — 169 ms — h2https://go.dev/images/logos/twitch.svg/images/logos/twitch.svg https://go.dev/images/logos/twitch.svg — 200 — 1.5 KiB — 236 ms — h2https://go.dev/images/logos/uber_light.svg/images/logos/uber_light.svg https://go.dev/images/logos/uber_light.svg — 200 — 2.9 KiB — 153 ms — h2https://go.dev/images/logos/x.png/images/logos/x.png https://go.dev/images/logos/x.png — 200 — 100.2 KiB — 292 ms — h2
HTML JavaScript CSS Images Fonts XHR/Fetch Other
Third-Party Script Cost
Per-script blocking time, transfer cost, and cache headers
INFO
78% of JavaScript execution is third-party
First-party Third-party 1226ms · 304KB · €13/mo
Unattributable
Other
Costly
Execution 570ms
Transfer 0 KB
Monthly Cost €6/mo
Google Tag Manager
Tag Manager
Costly
Execution 467ms
Transfer 160 KB
Unused 43%
Monthly Cost €5/mo
Google Tag Manager
Tag Manager
Optional
Execution 189ms
Transfer 144 KB
Unused 45%
Monthly Cost €2/mo

These scripts may cost more than they're worth

  • Unattributable adds 570ms and costs ~€6/month
  • Google Tag Manager adds 467ms and costs ~€5/month

78% 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 570ms 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 467ms 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.

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