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https://www.grammarly.com

Performance

· 14 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
71
GRADE
C
FIX
5
REVIEW
2
PASS
5
INFO
2

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

Mobile Desktop
65
Performance Overall performance score (0–100) based on Core Web Vitals and other metrics. 90+ is good.
97
Accessibility Measures how accessible the page is for users with disabilities. Checks color contrast, ARIA labels, and semantic HTML.
77
Best Practices Checks for modern web development best practices including HTTPS, no console errors, and secure JavaScript.
92
SEO Measures basic SEO optimizations: meta tags, crawlability, link text, and mobile friendliness.

First Contentful Paint First Contentful Paint — how long until the browser renders the first piece of content. Under 1.8s is good.

827 ms

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

1.58 s

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

634 ms

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

0.021

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

2.15 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.

6.69 s

Page Load Progression

894 ms
1.8 s
2.7 s
3.6 s
4.5 s
5.4 s
6.3 s
7.1 s
Checks
14
5 PASS 2 REVIEW 5 FIX
F
Page Weight Budget
Action
6.9 MB transferred, 201 requests
FIX
6.9 MB transferred, 201 requests
Critical::
Page weighs 13.9 MB (6.9 MB transferred)
Warning::
JavaScript is 2.5 MB — consider code splitting or lazy loading
Large JavaScript bundles delay interactivity. Split code by route or defer non-critical scripts.
Got: 2.5 MB
Info::
Fonts are 790 KB — consider subsetting or using system fonts
Subset fonts to include only used characters, or switch to system font stacks.
Got: 790 KB
Warning::
201 HTTP requests — consider bundling or reducing
Each request adds latency. Bundle small files, use sprites, or eliminate unnecessary requests.
Info::
Estimated 1.5 g CO2 per page load
6.9 MB / 2.4 MB budget
6.9 MB transferred
201 requests
1.5 g CO2 per page load
Other 3.2 MiB 46%
JavaScript 2.5 MiB 37%
Fonts 790.4 KiB 11%
Images 199.9 KiB 3%
CSS 88.0 KiB 1%
HTML 69.9 KiB 1%
Other 23.2 KiB 0%
Other 9.7 KiB 0%
Other 5.3 KiB 0%
Other 4.2 KiB 0%
Other 0 B 0%
0 2.4 MB 4.9 MB
Over budget

Large JavaScript bundles delay interactivity. Split code by route or defer non-critical scripts.

Why this matters

JavaScript bundle is large — code-split routes and lazy-load off-screen components to defer.

Source: web.dev

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

Each request adds latency. Bundle small files, use sprites, or eliminate unnecessary requests.

Why this matters

High HTTP request count — bundling, sprite-ing, and HTTP/2 server push can reduce per-request overhead.

Source: web.dev

D
Third-Party Impact
Action
99% third-party, 0 ms blocking
FIX
99% third-party, 0 ms blocking
Warning::
Third-party code accounts for 99% of page weight (6.9 MiB of 6.9 MiB)
Info::
Third-party blocking time is low (0 ms)
99%
First-party Third-party
D
JS Execution Cost
Action
2835ms total JS execution
FIX
2835ms total JS execution
Warning::
https://www.grammarly.com/: 571ms CPU time
Warning::
Unattributable: 483ms CPU time
Warning::
https://www.googletagmanager.com/gtm.js?id=GTM-NQ3...: 329ms CPU time
Warning::
https://static-web.grammarly.com/cms/master/_next/...: 253ms CPU time
Info::
https://static-web.grammarly.com/cms/master/_next/...: 219ms CPU time
Warning::
Third-party scripts: 2264ms (80% of total)

Main Thread Breakdown

Script Evaluation 57% Other 20% Style & Layout 8% Script Parsing & Compilation 8% Rendering 3%
ScriptTotalScriptingParse/CompileParty
https://www.grammarly.com/571ms44ms1ms1st
Unattributable483ms15ms0ms3rd
https://www.googletagmanager.com/gtm.js?id=GTM-NQ3XB9&l=dataLayerAt1333329ms266ms24ms3rd
https://static-web.grammarly.com/cms/master/_next/static/chunks/framework-18871a3a7164e80f.js253ms229ms5ms3rd
https://static-web.grammarly.com/cms/master/_next/static/chunks/pages/render-b5a9ba44889e5a7a.js219ms214ms0ms3rd
https://www.googletagmanager.com/gtag/js?id=AW-956476927&l=dataLayerAt1333&cx=c&gtm=4e6460147ms106ms24ms3rd
https://www.googletagmanager.com/gtag/js?id=G-CBK9K2ZWWE&l=dataLayerAt1333&cx=c&gtm=4e6460130ms110ms14ms3rd
https://transcend-cdn.com/cm/1c1f8e90-47d0-4bba-a1a2-472d59b002a2/airgap.js108ms92ms6ms3rd
https://www.googletagmanager.com/gtag/js?id=DC-11910764&l=dataLayerAt1333&cx=c&gtm=4e6460107ms97ms9ms3rd
https://analytics.tiktok.com/i18n/pixel/static/main.MWE0ZWQ3ZWQwMQ.js95ms80ms12ms3rd

Showing top 10 of 16 scripts

F
JS Bundles
Action
58 scripts, 1.1 MB unused
FIX
58 scripts, 1.1 MB unused
Warning::
https://static-web.grammarly.com/cms/master/_next/...: 317 KB unused (65%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://static-web.grammarly.com/cms/master/_next/...: 101 KB unused (63%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://static-web.grammarly.com/cms/master/_next/...: 81 KB unused (67%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://accounts.google.com/gsi/client: 70 KB unused (75%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.googletagmanager.com/gtag/js?id=DC-103...: 60 KB unused (46%)
Consider code splitting or tree shaking to reduce unused code.
Info::
Total unused JavaScript: 1.1 MB
1096 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://static-web.grammarly.com/cms/master/_next/static/chunks/345-b3c0ea41a809d894.js490 KB317 KB (65%)✓3rd
https://static-web.grammarly.com/cms/master/_next/static/chunks/151-c24adecc0ed805dc.js160 KB101 KB (63%)✓3rd
https://static-web.grammarly.com/cms/master/_next/static/chunks/2665999f-54d41965add03933.js122 KB81 KB (67%)✓3rd
https://accounts.google.com/gsi/client93 KB70 KB (75%)✓3rd
https://www.googletagmanager.com/gtag/js?id=DC-10353179&l=dataLayerAt1333&cx=c&gtm=4e6460130 KB60 KB (46%)✓3rd
https://www.googletagmanager.com/gtag/js?id=DC-10353176&l=dataLayerAt1333&cx=c&gtm=4e6460130 KB60 KB (46%)✓3rd
https://www.googletagmanager.com/gtag/js?id=G-CBK9K2ZWWE&l=dataLayerAt1333&cx=c&gtm=4e6460167 KB59 KB (36%)✓3rd
https://www.googletagmanager.com/gtm.js?id=GTM-NQ3XB9&l=dataLayerAt1333200 KB57 KB (28%)✓3rd
https://analytics.tiktok.com/i18n/pixel/static/main.MWE0ZWQ3ZWQwMQ.js110 KB56 KB (51%)✓3rd
https://www.googletagmanager.com/gtag/js?id=AW-956476927&l=dataLayerAt1333&cx=c&gtm=4e6460146 KB54 KB (37%)✓3rd

Consider code splitting or tree shaking to reduce unused code.

Why this matters

This bundle has high unused code — code-split or tree-shake to ship only what executes.

Source: web.dev / Lighthouse coverage

Consider code splitting or tree shaking to reduce unused code.

Why this matters

This bundle has high unused code — code-split or tree-shake to ship only what executes.

Source: web.dev / Lighthouse coverage

Consider code splitting or tree shaking to reduce unused code.

Why this matters

This bundle has high unused code — code-split or tree-shake to ship only what executes.

Source: web.dev / Lighthouse coverage

Consider code splitting or tree shaking to reduce unused code.

Why this matters

This bundle has high unused code — code-split or tree-shake to ship only what executes.

Source: web.dev / Lighthouse coverage

Consider code splitting or tree shaking to reduce unused code.

Why this matters

This bundle has high unused code — code-split or tree-shake to ship only what executes.

Source: web.dev / Lighthouse coverage

D
HTTP Caching
Action
no-store (uncacheable)
FIX
no-store (uncacheable)
Info::
Cache-Control: no-store prevents all caching
Intentional for dynamic content, but increases server load for every page view.
Got: max-age=0, no-store, no-cache
Info::
No ETag or Last-Modified header
Conditional requests (304 Not Modified) are not possible without validators.
Cache-Control

max-age=0, no-store, no-cache

DirectiveValueMeaning
max-age0Cache for 0 seconds
no-store—Never cache this response
no-cache—Cache but always revalidate first
C
Image Optimization
Action
51 images, 0 KB saveable
REVIEW
51 images, 0 KB saveable
Warning::
data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAGQA... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
51 images 200 KB
0 oversized -0 KB
43 legacy format
2 missing dimensions CLS risk

Set explicit width and height to prevent CLS.

Why this matters

Image without explicit width/height — browser can't reserve space; CLS jumps when image loads.

Source: web.dev / Core Web Vitals

Set explicit width and height to prevent CLS.

Why this matters

Performance issues directly impact user engagement and conversion rates.

C
Green Hosting
Action
Whether the site is served from green-energy infrastructure
REVIEW

Green Hosting

No green hosting detected

A+
Text Compression
All text resources are compressed
PASS
All text resources are compressed
Info::
All text resources are compressed
All text resources are properly compressed.
A+
Font Loading
10 fonts (790 KB)
PASS
10 fonts (790 KB)
Info::
10 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

10

790 KB total

Render-blocking

0

of 10

Dominant font-display

swap

Most common across fonts

Font loading timeline
Transfer FOIT (block) FOUT (swap)
0 ms 500 ms 1.0 s 1.5 s FCP 827 ms LCP 1.6 shttps://static-web.grammarly.com/shared/fonts/inter-regular.woff2inter-regular.woff2 https://static-web.grammarly.com/shared/fonts/inter-regular.woff2 — 91.1 KiB — 0 ms — font-display: swaphttps://static-web.grammarly.com/shared/fonts/inter-medium.woff2inter-medium.woff2 https://static-web.grammarly.com/shared/fonts/inter-medium.woff2 — 187.0 KiB — 0 ms — font-display: swaphttps://static-web.grammarly.com/shared/fonts/inter-semi-bold.woff2inter-semi-bold.woff2 https://static-web.grammarly.com/shared/fonts/inter-semi-bold.woff2 — 188.1 KiB — 0 ms — font-display: swaphttps://static-web.grammarly.com/shared/fonts/inter-bold.woff2inter-bold.woff2 https://static-web.grammarly.com/shared/fonts/inter-bold.woff2 — 97.8 KiB — 0 ms — font-display: swaphttps://static-web.grammarly.com/shared/fonts/matter-medium.woff2matter-medium.woff2 https://static-web.grammarly.com/shared/fonts/matter-medium.woff2 — 31.6 KiB — 0 ms — font-display: swaphttps://static-web.grammarly.com/shared/fonts/matter-semi-bold.woff2matter-semi-bold.woff2 https://static-web.grammarly.com/shared/fonts/matter-semi-bold.woff2 — 31.4 KiB — 0 ms — font-display: swaphttps://static-web.grammarly.com/cms/master/public/fonts/MatterforGrammarlyVF.woff2MatterforGrammarlyVF.woff2 https://static-web.grammarly.com/cms/master/public/fonts/MatterforGrammarlyVF.woff2 — 33.8 KiB — 0 ms — font-display: swaphttps://static-web.grammarly.com/shared/fonts/glyph-regular.woff2glyph-regular.woff2 https://static-web.grammarly.com/shared/fonts/glyph-regular.woff2 — 35.9 KiB — 0 ms — font-display: swaphttps://static-web.grammarly.com/shared/fonts/glyph-bold.woff2glyph-bold.woff2 https://static-web.grammarly.com/shared/fonts/glyph-bold.woff2 — 36.3 KiB — 0 ms — font-display: swaphttps://static-web.grammarly.com/cms/master/public/fonts/MessinaSerifWeb-VF-Upright.woff2MessinaSerifWeb-VF-Upri... https://static-web.grammarly.com/cms/master/public/fonts/MessinaSerifWeb-VF-Upright.woff2 — 57.4 KiB — 0 ms — font-display: swap
inter-regular.woff2 woff2 swap
Size 91 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
inter-medium.woff2 woff2 swap
Size 187 KB
Load time 0 ms
Start 0 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
inter-semi-bold.woff2 woff2 swap
Size 188 KB
Load time 0 ms
Start 0 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
inter-bold.woff2 woff2 swap
Size 98 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
matter-medium.woff2 woff2 swap
Size 32 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
matter-semi-bold.woff2 woff2 swap
Size 31 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
MatterforGrammarlyVF.woff2 woff2 swap
Size 34 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
glyph-regular.woff2 woff2 swap
Size 36 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
glyph-bold.woff2 woff2 swap
Size 36 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
MessinaSerifWeb-VF-Upri... woff2 swap
Size 57 KB
Load time 0 ms
Start 0 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)

Fixing the unchecked items could save ~188 KB and ~376 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
Network Waterfall
201 requests over 0ms
INFO

Performance analysis not available for this result.

Third-Party Script Cost
Per-script blocking time, transfer cost, and cache headers
INFO
80% of JavaScript execution is third-party
First-party Third-party 2264ms · 1364KB · $30/mo
Unattributable
Other
Costly
Execution 483ms
Transfer 0 KB
Monthly Cost $6/mo
Google Tag Manager
Tag Manager
Costly
Execution 329ms
Transfer 200 KB
Unused 28%
Monthly Cost $4/mo
static-web.grammarly.com
Other
Costly
Execution 253ms
Transfer 54 KB
Unused 45%
Monthly Cost $3/mo
static-web.grammarly.com
Other
Costly
Execution 219ms
Transfer 1 KB
Monthly Cost $3/mo
Google Tag Manager
Tag Manager
Optional
Execution 147ms
Transfer 146 KB
Unused 37%
Monthly Cost $2/mo
Google Tag Manager
Tag Manager
Optional
Execution 130ms
Transfer 167 KB
Unused 36%
Monthly Cost $2/mo
transcend-cdn.com
Other
Optional
Execution 108ms
Transfer 53 KB
Unused 44%
Monthly Cost $1/mo
Google Tag Manager
Tag Manager
Optional
Execution 107ms
Transfer 131 KB
Unused 41%
Monthly Cost $1/mo
analytics.tiktok.com
Other
Optional
Execution 95ms
Transfer 110 KB
Unused 51%
Monthly Cost $1/mo
Google Tag Manager
Tag Manager
Optional
Execution 84ms
Transfer 130 KB
Unused 46%
Monthly Cost $1/mo
Google Tag Manager
Tag Manager
Optional
Execution 71ms
Transfer 130 KB
Unused 46%
Monthly Cost $1/mo
Microsoft Clarity
Session Replay
Optional
Execution 65ms
Transfer 26 KB
Monthly Cost $1/mo
Facebook Pixel
Advertising
Optional
Execution 64ms
Transfer 95 KB
Unused 36%
Monthly Cost $1/mo
transcend-cdn.com
Other
Optional
Execution 58ms
Transfer 93 KB
Unused 48%
Monthly Cost $1/mo
cdn.taboola.com
Other
Optional
Execution 52ms
Transfer 27 KB
Monthly Cost $1/mo

These scripts may cost more than they're worth

  • Unattributable adds 483ms and costs ~$6/month
  • Google Tag Manager adds 329ms and costs ~$4/month
  • static-web.grammarly.com adds 253ms and costs ~$3/month
  • static-web.grammarly.com adds 219ms and costs ~$3/month

80% 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 483ms 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 329ms 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

static-web.grammarly.com takes 253ms 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

static-web.grammarly.com takes 219ms 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

51% of analytics.tiktok.com's code is unused. The script may be loading features you don't use.

Why this matters

Bundle has high unused-code ratio — tree-shaking and route-splitting recover the wasted bytes.

Source: web.dev

How third-party costs are calculated

All checks on this page are automated. Results are estimates - run targeted manual reviews when the score affects a release decision.

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