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https://story-viewer.online

Performance

· 26 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
95
GRADE
A
FIX
1
REVIEW
3
PASS
19
INFO
3

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

Mobile Desktop
83
Performance Overall performance score (0–100) based on Core Web Vitals and other metrics. 90+ is good.
90
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.
91
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.

1.09 s

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

4.38 s

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

121 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.

2.96 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.

4.59 s

Page Load Progression

522 ms
1.0 s
1.6 s
2.1 s
2.6 s
3.1 s
3.7 s
4.2 s
Checks
26
19 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.

C
JS Execution Cost
Action
1823ms total JS execution
REVIEW
1823ms total JS execution
Warning::
https://story-viewer.online/_next/static/chunks/67...: 446ms CPU time
Warning::
https://story-viewer.online/: 439ms CPU time
Warning::
https://story-viewer.online/_next/static/chunks/87...: 369ms CPU time
Info::
https://scripts.clarity.ms/0.8.69/clarity.js: 245ms CPU time
Info::
Unattributable: 201ms CPU time
Info::
Third-party scripts: 245ms (13% of total)

Main Thread Breakdown

Script Evaluation 52% Other 23% Style & Layout 16% Script Parsing & Compilation 4% Rendering 4%
ScriptTotalScriptingParse/CompileParty
https://story-viewer.online/_next/static/chunks/6733-006ecefe29f53e21.js446ms293ms10ms1st
https://story-viewer.online/439ms12ms8ms1st
https://story-viewer.online/_next/static/chunks/8724-0e5a48a498da935b.js369ms353ms10ms1st
https://scripts.clarity.ms/0.8.69/clarity.js245ms206ms7ms3rd
Unattributable201ms8ms0ms1st
https://story-viewer.online/_next/static/chunks/07f299c6-a37406445cb891f5.js63ms16ms20ms1st
https://story-viewer.online/_next/static/chunks/app/%5Blocale%5D/layout-3604ed1dce9aba22.js60ms59ms1ms1st
B
Main HTML Cache-Control
No Cache-Control header on main HTML response
REVIEW
No Cache-Control header on main HTML response
Info::
Main HTML response has no Cache-Control header
Without an explicit Cache-Control, browsers fall back to heuristic caching (~10% of Last-Modified age). Set `Cache-Control: no-cache` or `max-age=300` for HTML to control freshness explicitly -- prevents stale auth state and SPA shell drift.
B
Server-Timing Observability
No Server-Timing header found
REVIEW
No Server-Timing header found
Info::
No Server-Timing header found
Server-Timing exposes backend timing breakdowns to browser DevTools (e.g., `db: 45ms; render: 120ms; cache: 2ms`). Useful for diagnosing slow pages without backend log access. Most modern frameworks (Next.js, Cloudflare Workers, Fastly) emit it automatically; absence on a managed platform usually means telemetry headers are stripped at the edge.
A+
Page Weight Budget
299 KB transferred, 27 requests
PASS
299 KB transferred, 27 requests
Info::
Page weighs 963 KB (299 KB transferred)
Info::
27 HTTP requests
Info::
Estimated 0.06 g CO2 per page load
299 KB / 2.4 MB budget
299 KB transferred
27 requests
0.06 g CO2 per page load
JavaScript 229.8 KiB 77%
Fonts 31.0 KiB 10%
HTML 19.5 KiB 7%
CSS 15.9 KiB 5%
Other 1.1 KiB 0%
Other 849 B 0%
Other 814 B 0%
Other 0 B 0%
0 2.4 MB 4.9 MB
Under budget
A+
Third-Party Impact
10% third-party, 0 ms blocking
PASS
10% third-party, 0 ms blocking
Info::
Third-party code accounts for 10% of page weight (31.2 KiB of 298.9 KiB)
Info::
Third-party blocking time is low (0 ms)
90%
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+
Image Optimization
No images on this page
PASS
No images on this page
Info::
No images on this page
0 images 0 KB
0 oversized -0 KB
0 legacy format
0 missing dimensions CLS risk
A+
Font Loading
1 fonts (31 KB)
PASS
1 fonts (31 KB)
Info::
1 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

1

31 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 FCP 1.1 s LCP 4.4 shttps://story-viewer.online/_next/static/media/558ca1a6aa3cb55e-s.p.woff2558ca1a6aa3cb55e-s.p.woff2 https://story-viewer.online/_next/static/media/558ca1a6aa3cb55e-s.p.woff2 — 31.0 KiB — 31 ms — font-display: swap
558ca1a6aa3cb55e-s.p.woff2 woff2 swap
Size 31 KB
Load time 31 ms
Start 209 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+
JS Bundles
16 scripts, 23 KB unused
PASS
16 scripts, 23 KB unused
Warning::
https://story-viewer.online/_next/static/chunks/67...: 23 KB unused (54%)
Consider code splitting or tree shaking to reduce unused code.
Info::
Total unused JavaScript: 23 KB
23 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://story-viewer.online/_next/static/chunks/6733-006ecefe29f53e21.js42 KB23 KB (54%)✓1st
https://story-viewer.online/_next/static/chunks/7523-0eeadfca7ab75e1c.js9 KB—✓1st
https://story-viewer.online/_next/static/chunks/2554-3d26d28db2653ea6.js6 KB—✓1st
https://story-viewer.online/_next/static/chunks/main-app-e1a600ff156106ca.js1 KB—✓1st
https://story-viewer.online/_next/static/chunks/07f299c6-a37406445cb891f5.js54 KB—✓1st
https://story-viewer.online/_next/static/chunks/5892-b54ba5813f276bda.js4 KB—✓1st
https://story-viewer.online/_next/static/chunks/9801-f8b5bc5b43b4ee4e.js16 KB—✓1st
https://story-viewer.online/_next/static/chunks/8724-0e5a48a498da935b.js44 KB—✓1st
https://story-viewer.online/_next/static/chunks/app/%5Blocale%5D/page-19cf22cf7279ecd8.js11 KB—✓1st
https://story-viewer.online/_next/static/chunks/9578-e413bd6f8750b4ae.js6 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

A+
Resource Caching
All resources properly cached
PASS
All resources properly cached
Info::
No caching issues found
All static resources have appropriate caching headers.
A+
Critical Rendering Path
No render-blocking resources
PASS
No render-blocking resources
Info::
No render-blocking resources detected
A+
Resource Hints
2 hints, 0 missing preconnects
PASS
2 hints, 0 missing preconnects
Info::
Page uses 2 resource hint(s)

Current Resource Hints

preconnect
—
preload
2
dns-prefetch
—
prefetch
—

2 resource hints configured

A+
HTTP/3 (QUIC)
HTTP/3 advertised via Alt-Svc
PASS
HTTP/3 advertised via Alt-Svc
Info::
HTTP/3 (QUIC) is supported
First-load mobile users on cellular networks see meaningful latency improvements with HTTP/3. The QUIC transport collapses TLS + TCP handshakes into one and recovers faster from packet loss.
A+
Document Compression
Document response uses brotli
PASS
Document response uses brotli
Info::
Main HTML response uses brotli (Content-Encoding: br)
Brotli is the best text-compression algorithm for general use, ~20% smaller than gzip on average (40% on smaller files). Modern browsers all support it.
A+
LCP Image Preload
LCP preload audit not available
PASS
LCP preload audit not available
Info::
LCP image preload audit not available for this scan
A+
Server Response Intelligence
2 server-response signal(s) detected
PASS
2 server-response signal(s) detected
Info::
`Vary` header declared: rsc, next-router-state-tree, next-router-prefetch, next-router-segment-prefetch
The page declares a `Vary` header, telling downstream caches which request headers the response varies on. Critical for content-negotiated responses (compression, language, cookies, device class).
Info::
No `ETag` or `Last-Modified` -- conditional GET not supported
Without either header, browsers can't issue conditional GETs and refresh always re-downloads the full response body even when nothing changed. Add `ETag: "<hash>"` (or `Last-Modified: <date>`) on cacheable responses; the server returns 304 Not Modified when the client's cached copy is still valid, saving bandwidth.
A+
Page Weight Inventory
27 resources · 299 KB · 23 KB savings available
PASS
27 resources · 299 KB · 23 KB savings available
Info::
Within 1MB page-weight target
Got: 299 KB
Info::
8 third-party resources (10% of weight)
27 resources · 298.9 KiB · 8 third-party Within 1MB page-weight target
JavaScript 77% · 229.8 KiB
Font 10% · 31.0 KiB
Document 7% · 19.5 KiB
CSS 5% · 15.9 KiB
Other 1% · 1.9 KiB
Image 0% · 814 B

~22.5 KiB of savings available

Remove unused JavaScript: 22.5 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
JavaScript Blocking
1 JS blocking issue(s) detected
PASS
1 JS blocking issue(s) detected
Warning::
1 render-blocking <script src> tag(s) without async/defer
Each `<script src=...>` without `async`, `defer`, or `type="module"` blocks HTML parsing while the browser fetches and executes it. The block lasts the entire round-trip + execution time -- on slow networks this translates directly into LCP delay. Add `defer` (executes after parse, in source order) for scripts that interact with the DOM, or `async` (executes whenever ready) for analytics / independent scripts. Module scripts (`type="module"`) are deferred by default.
A+
CSS Performance Depth
No CSS performance depth issues detected
PASS
No CSS performance depth issues detected
Info::
No CSS performance depth issues 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: Cloudflare

Asset Compression
No text asset hosts to measure
INFO
No text asset hosts to measure
Info::
No third-party or subdomain host served enough text assets to measure
Asset compression is measured per host, from one HEAD request against a sampled resource. Pages that serve all their JS and CSS from the document's own origin are covered by the document compression check instead.
Network Waterfall
27 requests over 3773ms
INFO
0 ms 1.0 s 2.0 s 3.0 s 4.0 s FCP 1.1 s LCP 4.4 shttps://story-viewer.online// https://story-viewer.online/ — 200 — 19.5 KiB — 200 ms — h2https://story-viewer.online/_next/static/media/558ca1a6aa3cb55e-s.p.woff2/_next/static/media/558ca1a6aa3cb55... https://story-viewer.online/_next/static/media/558ca1a6aa3cb55e-s.p.woff2 — 200 — 31.0 KiB — 31 ms — h2https://story-viewer.online/_next/static/css/743b9d060301fdad.css/_next/static/css/743b9d060301fdad.... https://story-viewer.online/_next/static/css/743b9d060301fdad.css — 200 — 14.9 KiB — 36 ms — h2https://story-viewer.online/_next/static/css/89792a0008d572c3.css/_next/static/css/89792a0008d572c3.... https://story-viewer.online/_next/static/css/89792a0008d572c3.css — 200 — 1023 B — 35 ms — h2https://story-viewer.online/_next/static/chunks/webpack-46e3d22794a2ed69.js/_next/static/chunks/webpack-46e3d2... https://story-viewer.online/_next/static/chunks/webpack-46e3d22794a2ed69.js — 200 — 2.2 KiB — 57 ms — h3https://story-viewer.online/_next/static/chunks/07f299c6-a37406445cb891f5.js/_next/static/chunks/07f299c6-a3740... https://story-viewer.online/_next/static/chunks/07f299c6-a37406445cb891f5.js — 200 — 53.7 KiB — 42 ms — h3https://story-viewer.online/_next/static/chunks/8724-0e5a48a498da935b.js/_next/static/chunks/8724-0e5a48a49... https://story-viewer.online/_next/static/chunks/8724-0e5a48a498da935b.js — 200 — 44.0 KiB — 72 ms — h3https://story-viewer.online/_next/static/chunks/main-app-e1a600ff156106ca.js/_next/static/chunks/main-app-e1a60... https://story-viewer.online/_next/static/chunks/main-app-e1a600ff156106ca.js — 200 — 771 B — 66 ms — h3https://story-viewer.online/_next/static/chunks/6733-006ecefe29f53e21.js/_next/static/chunks/6733-006ecefe2... https://story-viewer.online/_next/static/chunks/6733-006ecefe29f53e21.js — 200 — 42.0 KiB — 77 ms — h3https://story-viewer.online/_next/static/chunks/5892-b54ba5813f276bda.js/_next/static/chunks/5892-b54ba5813... https://story-viewer.online/_next/static/chunks/5892-b54ba5813f276bda.js — 200 — 4.0 KiB — 66 ms — h3https://story-viewer.online/_next/static/chunks/9801-f8b5bc5b43b4ee4e.js/_next/static/chunks/9801-f8b5bc5b4... https://story-viewer.online/_next/static/chunks/9801-f8b5bc5b43b4ee4e.js — 200 — 16.4 KiB — 67 ms — h3https://story-viewer.online/_next/static/chunks/9578-e413bd6f8750b4ae.js/_next/static/chunks/9578-e413bd6f8... https://story-viewer.online/_next/static/chunks/9578-e413bd6f8750b4ae.js — 200 — 6.2 KiB — 89 ms — h3https://story-viewer.online/_next/static/chunks/7523-0eeadfca7ab75e1c.js/_next/static/chunks/7523-0eeadfca7... https://story-viewer.online/_next/static/chunks/7523-0eeadfca7ab75e1c.js — 200 — 8.7 KiB — 86 ms — h3https://story-viewer.online/_next/static/chunks/app/%5Blocale%5D/page-19cf22cf7279ecd8.js/_next/static/chunks/app/%5Blocale%... https://story-viewer.online/_next/static/chunks/app/%5Blocale%5D/page-19cf22cf7279ecd8.js — 200 — 11.2 KiB — 86 ms — h3https://story-viewer.online/_next/static/chunks/4036-1859004ac8f027ff.js/_next/static/chunks/4036-1859004ac... https://story-viewer.online/_next/static/chunks/4036-1859004ac8f027ff.js — 200 — 3.8 KiB — 86 ms — h3https://story-viewer.online/_next/static/chunks/2554-3d26d28db2653ea6.js/_next/static/chunks/2554-3d26d28db... https://story-viewer.online/_next/static/chunks/2554-3d26d28db2653ea6.js — 200 — 5.6 KiB — 87 ms — h3https://story-viewer.online/_next/static/chunks/app/%5Blocale%5D/layout-3604ed1dce9aba22.js/_next/static/chunks/app/%5Blocale%... https://story-viewer.online/_next/static/chunks/app/%5Blocale%5D/layout-3604ed1dce9aba22.js — 200 — 1.9 KiB — 86 ms — h3https://umami.bestvid.net/script.jsumami.bestvid.net/script.js https://umami.bestvid.net/script.js — 200 — 3.0 KiB — 118 ms — h3https://www.clarity.ms/tag/ux4odi49vtwww.clarity.ms/tag/ux4odi49vt https://www.clarity.ms/tag/ux4odi49vt — 200 — 1.1 KiB — 155 ms — http/1.1https://scripts.clarity.ms/0.8.69/clarity.jsscripts.clarity.ms/0.8.69/clarity.j... https://scripts.clarity.ms/0.8.69/clarity.js — 200 — 25.2 KiB — 202 ms — h2https://umami.bestvid.net/api/sendumami.bestvid.net/api/send https://umami.bestvid.net/api/send — 204 — 0 B — 128 ms — h3https://story-viewer.online/icon.png/icon.png https://story-viewer.online/icon.png — 200 — 0 B — 2 ms — h3https://story-viewer.online/icon.svg/icon.svg https://story-viewer.online/icon.svg — 200 — 814 B — 70 ms — h3https://u.clarity.ms/collectu.clarity.ms/collect https://u.clarity.ms/collect — 204 — 283 B — 339 ms — http/1.1https://umami.bestvid.net/api/sendumami.bestvid.net/api/send https://umami.bestvid.net/api/send — 200 — 1.1 KiB — 61 ms — h3https://u.clarity.ms/collectu.clarity.ms/collect https://u.clarity.ms/collect — 204 — 283 B — 200 ms — http/1.1https://u.clarity.ms/collectu.clarity.ms/collect https://u.clarity.ms/collect — 204 — 283 B — 100 ms — http/1.1
HTML JavaScript CSS Images Fonts XHR/Fetch Other
Third-Party Script Cost
Per-script blocking time, transfer cost, and cache headers
INFO
13% of JavaScript execution is third-party
First-party Third-party 245ms · 25KB · €3/mo
Microsoft Clarity
Session Replay
Costly
Execution 245ms
Transfer 25 KB
Monthly Cost €3/mo

These scripts may cost more than they're worth

  • Microsoft Clarity adds 245ms and costs ~€3/month

Microsoft Clarity takes 245ms 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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