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Performance

· 15 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
87
GRADE
B
FIX
1
REVIEW
3
PASS
9
INFO
2

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

Mobile Desktop
98
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.

640 ms

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

1.10 s

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

0 ms

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

0.017

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

727 ms

Time to Interactive Time to Interactive — how long until the page is fully interactive and responds to user input. Under 3.8s is good.

1.11 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
15
9 PASS 3 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 (450.5 KiB of 842.1 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/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/stack-overflow.... 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/icons/sphere.svg 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/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/slack.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/reddit.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/icons/command-folder.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/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/mastodon.svg is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
46 images 252 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

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=4e64k0h2144 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
842 KB transferred, 70 requests
PASS
842 KB transferred, 70 requests
Info::
Page weighs 1.7 MB (842 KB transferred)
Info::
70 HTTP requests
Info::
Estimated 0.17 g CO2 per page load
842 KB / 2.4 MB budget
842 KB transferred
70 requests
0.17 g CO2 per page load
JavaScript 380.6 KiB 45%
Images 252.1 KiB 30%
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+
JS Execution Cost
378ms total JS execution
PASS
378ms total JS execution
Info::
Unattributable: 142ms CPU time
Info::
https://www.googletagmanager.com/gtm.js?id=GTM-W8M...: 136ms CPU time
Info::
https://go.dev/: 101ms CPU time
Warning::
Third-party scripts: 278ms (73% of total)

Main Thread Breakdown

Script Evaluation 37% Other 31% Style & Layout 14% Script Parsing & Compilation 11% Rendering 4%
ScriptTotalScriptingParse/CompileParty
Unattributable142ms3ms0ms3rd
https://www.googletagmanager.com/gtm.js?id=GTM-W8MVQXG136ms88ms38ms3rd
https://go.dev/101ms5ms1ms1st
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 500 ms 1.0 s FCP 640 ms LCP 1.1 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 — 69 ms — font-display: swap
flUhRq6tzZclQEJ-Vdg-Iui... woff2 swap
Size 126 KB
Load time 69 ms
Start 463 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
No optimization needed
PASS
No optimization needed
Info::
No resource hint issues
A
Page Weight Inventory
70 resources · 842 KB · 132 KB savings available
PASS
70 resources · 842 KB · 132 KB savings available
Info::
Within 1MB page-weight target
Got: 842 KB
Info::
~132 KB of savings available
Warning::
6 third-party resources (54% of weight)
70 resources · 842.1 KiB · 6 third-party Within 1MB page-weight target
JavaScript 45% · 380.6 KiB
Image 34% · 283.4 KiB
Font 15% · 125.6 KiB
CSS 3% · 27.2 KiB
Document 2% · 12.7 KiB
Other 1% · 12.6 KiB

~131.9 KiB of savings available

Remove unused JavaScript: 131.9 KiB
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 2341ms
INFO
0 ms 500 ms 1.0 s 1.5 s 2.0 s FCP 640 ms LCP 1.1 shttps://go.dev// https://go.dev/ — 200 — 12.7 KiB — 165 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 — 75 ms — h2https://go.dev/css/styles.css/css/styles.css https://go.dev/css/styles.css — 200 — 26.4 KiB — 176 ms — h2https://go.dev/js/site.js/js/site.js https://go.dev/js/site.js — 200 — 3.8 KiB — 164 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 — 203 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 — 154 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 — 149 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 — 270 ms — h2https://go.dev/js/jquery.js/js/jquery.js https://go.dev/js/jquery.js — 200 — 35.6 KiB — 306 ms — h2https://go.dev/js/carousels.js/js/carousels.js https://go.dev/js/carousels.js — 200 — 1.9 KiB — 159 ms — h2https://go.dev/js/searchBox.js/js/searchBox.js https://go.dev/js/searchBox.js — 200 — 1.1 KiB — 283 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 — 162 ms — h2https://go.dev/js/playground.js/js/playground.js https://go.dev/js/playground.js — 200 — 5.9 KiB — 245 ms — h2https://go.dev/js/godocs.js/js/godocs.js https://go.dev/js/godocs.js — 200 — 4.3 KiB — 173 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 — 176 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 — 170 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 — 267 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 — 726 B — 271 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 — 173 ms — h2https://go.dev/images/gophers/ladder.svg/images/gophers/ladder.svg https://go.dev/images/gophers/ladder.svg — 200 — 18.3 KiB — 254 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 — 177 ms — h2https://go.dev/images/icons/sphere.svg/images/icons/sphere.svg https://go.dev/images/icons/sphere.svg — 200 — 5.5 KiB — 181 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 — 170 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 — 179 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 — 167 ms — h2https://go.dev/images/icons/code.svg/images/icons/code.svg https://go.dev/images/icons/code.svg — 200 — 1.1 KiB — 174 ms — h2https://go.dev/images/icons/gear-dark.svg/images/icons/gear-dark.svg https://go.dev/images/icons/gear-dark.svg — 200 — 987 B — 193 ms — h2
0 ms 500 ms 1.0 s 1.5 s 2.0 s FCP 640 ms LCP 1.1 shttps://go.dev// https://go.dev/ — 200 — 12.7 KiB — 165 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 — 75 ms — h2https://go.dev/css/styles.css/css/styles.css https://go.dev/css/styles.css — 200 — 26.4 KiB — 176 ms — h2https://go.dev/js/site.js/js/site.js https://go.dev/js/site.js — 200 — 3.8 KiB — 164 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 — 203 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 — 154 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 — 149 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 — 270 ms — h2https://go.dev/js/jquery.js/js/jquery.js https://go.dev/js/jquery.js — 200 — 35.6 KiB — 306 ms — h2https://go.dev/js/carousels.js/js/carousels.js https://go.dev/js/carousels.js — 200 — 1.9 KiB — 159 ms — h2https://go.dev/js/searchBox.js/js/searchBox.js https://go.dev/js/searchBox.js — 200 — 1.1 KiB — 283 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 — 162 ms — h2https://go.dev/js/playground.js/js/playground.js https://go.dev/js/playground.js — 200 — 5.9 KiB — 245 ms — h2https://go.dev/js/godocs.js/js/godocs.js https://go.dev/js/godocs.js — 200 — 4.3 KiB — 173 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 — 176 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 — 170 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 — 267 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 — 726 B — 271 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 — 173 ms — h2https://go.dev/images/gophers/ladder.svg/images/gophers/ladder.svg https://go.dev/images/gophers/ladder.svg — 200 — 18.3 KiB — 254 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 — 177 ms — h2https://go.dev/images/icons/sphere.svg/images/icons/sphere.svg https://go.dev/images/icons/sphere.svg — 200 — 5.5 KiB — 181 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 — 170 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 — 179 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 — 167 ms — h2https://go.dev/images/icons/code.svg/images/icons/code.svg https://go.dev/images/icons/code.svg — 200 — 1.1 KiB — 174 ms — h2https://go.dev/images/icons/gear-dark.svg/images/icons/gear-dark.svg https://go.dev/images/icons/gear-dark.svg — 200 — 987 B — 193 ms — h2https://go.dev/images/icons/gear.svg/images/icons/gear.svg https://go.dev/images/icons/gear.svg — 200 — 982 B — 198 ms — h2https://go.dev/js/index.js/js/index.js https://go.dev/js/index.js — 200 — 583 B — 184 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 — 190 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 — 394 B — 195 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 — 375 B — 185 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 — 191 ms — h2https://go.dev/images/google-white.png/images/google-white.png https://go.dev/images/google-white.png — 200 — 6.3 KiB — 182 ms — h2https://go.dev/js/copypaste.js/js/copypaste.js https://go.dev/js/copypaste.js — 200 — 435 B — 186 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 — 159.6 KiB — 148 ms — h2https://go.dev/images/logos/google.svg/images/logos/google.svg https://go.dev/images/logos/google.svg — 200 — 2.3 KiB — 168 ms — h2https://go.dev/images/logos/paypal.svg/images/logos/paypal.svg https://go.dev/images/logos/paypal.svg — 200 — 1.8 KiB — 163 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 — 161 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 — 189 ms — h2https://go.dev/images/logos/bitly.svg/images/logos/bitly.svg https://go.dev/images/logos/bitly.svg — 200 — 4.0 KiB — 166 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 — 159 ms — h2https://go.dev/images/logos/cockroach.svg/images/logos/cockroach.svg https://go.dev/images/logos/cockroach.svg — 200 — 606 B — 162 ms — h2https://go.dev/images/logos/dropbox.png/images/logos/dropbox.png https://go.dev/images/logos/dropbox.png — 200 — 3.0 KiB — 156 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 — 173 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 — 172 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 — 181 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 — 177 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 — 212 ms — h2https://go.dev/images/logos/netflix.svg/images/logos/netflix.svg https://go.dev/images/logos/netflix.svg — 200 — 998 B — 176 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 — 181 ms — h2https://go.dev/images/logos/salesforce.svg/images/logos/salesforce.svg https://go.dev/images/logos/salesforce.svg — 200 — 6.1 KiB — 194 ms — h2https://go.dev/images/logos/twitch.svg/images/logos/twitch.svg https://go.dev/images/logos/twitch.svg — 200 — 1.5 KiB — 164 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 — 174 ms — h2https://go.dev/images/logos/x.png/images/logos/x.png https://go.dev/images/logos/x.png — 200 — 100.2 KiB — 293 ms — h2https://go.dev/images/gophers/biplane.svg/images/gophers/biplane.svg https://go.dev/images/gophers/biplane.svg — 200 — 11.7 KiB — 165 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 — 69 ms — h3https://www.googletagmanager.com/gtag/js?id=G-HL38R6X1Q3&cx=c&gtm=4e64k0h2www.googletagmanager.com/gtag/js?id... https://www.googletagmanager.com/gtag/js?id=G-HL38R6X1Q3&cx=c&gtm=4e64k0h2 — 200 — 143.6 KiB — 56 ms — h2https://www.google-analytics.com/analytics.jswww.google-analytics.com/analytics.... https://www.google-analytics.com/analytics.js — 200 — 20.9 KiB — 113 ms — h2https://www.google.com/ccm/collect?rcb=19&frm=0&ae=g&en=page_view&dl=https%3A%2F%2Fgo.dev%2F&scrsrc=www.googletagmanager.com&rnd=382508277.1776802187&dt=The%20Go%20Programming%20Language&auid=1624539794.1776802187&navt=n&npa=1&ep.ads_data_redaction=0&gtm=45He64k0h2v830425926za200zd830425926xea&gcd=13l3l3l2l1l1&dma_cps=a&dma=1&tag_exp=0~115938465~115938468~117266400~117384406~118463262&apve=1&apvf=f&apvc=1&tft=1776802186646&tfd=681www.google.com/ccm/collect?rcb=19&f... https://www.google.com/ccm/collect?rcb=19&frm=0&ae=g&en=page_view&dl=https%3A%2F%2Fgo.dev%2F&scrsrc=www.googletagmanager.com&rnd=382508277.1776802187&dt=The%20Go%20Programming%20Language&auid=1624539794.1776802187&navt=n&npa=1&ep.ads_data_redaction=0&gtm=45He64k0h2v830425926za200zd830425926xea&gcd=13l3l3l2l1l1&dma_cps=a&dma=1&tag_exp=0~115938465~115938468~117266400~117384406~118463262&apve=1&apvf=f&apvc=1&tft=1776802186646&tfd=681 — -1 — 0 B — 70 ms — https://go.dev/dl/?mode=json/dl/?mode=json https://go.dev/dl/?mode=json — 200 — 5.9 KiB — 193 ms — h2https://go.dev/dl/?mode=json/dl/?mode=json https://go.dev/dl/?mode=json — 200 — 5.9 KiB — 441 ms — h2https://go.dev/doc/play/hello.go/doc/play/hello.go https://go.dev/doc/play/hello.go — 200 — 245 B — 150 ms — h2https://go.dev/images/favicon-gopher.svg/images/favicon-gopher.svg https://go.dev/images/favicon-gopher.svg — 200 — 17.5 KiB — 156 ms — h2https://go.dev/_/fmt?backend=/_/fmt?backend= https://go.dev/_/fmt?backend= — 200 — 271 B — 172 ms — h2https://go.dev/images/favicon-gopher.png/images/favicon-gopher.png https://go.dev/images/favicon-gopher.png — 200 — 13.8 KiB — 155 ms — h2https://go.dev/_/compile?backend=/_/compile?backend= https://go.dev/_/compile?backend= — 200 — 263 B — 1.2 s — h2
HTML JavaScript CSS Images Fonts XHR/Fetch Other
Third-Party Script Cost
Per-script blocking time, transfer cost, and cache headers
INFO
73% of JavaScript execution is third-party
First-party Third-party 278ms · 160KB · €3/mo
Unattributable
Other
Optional
Execution 142ms
Transfer 0 KB
Monthly Cost €2/mo
Google Tag Manager
Tag Manager
Optional
Execution 136ms
Transfer 160 KB
Unused 43%
Monthly Cost €1/mo

73% 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

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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