https://story-viewer.online
Performance
· 22 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.SCORE
95
GRADE
A
FIX
1
REVIEW
3
PASS
15
INFO
3
Performance-focused optimization plan with CWV assessment, top offenders, and time estimates
100
96
100
91
First Contentful Paint First Contentful Paint — how long until the browser renders the first piece of content. Under 1.8s is good.
398 ms
Largest Contentful Paint Largest Contentful Paint — how long until the largest visible element loads. Under 2.5s is good.
740 ms
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.
0.000
Speed Index Speed Index — how quickly content is visually displayed during load. Under 3.4s is good.
496 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.
740 ms
Page Load Progression
375 ms
750 ms
1.1 s 1.5 s
1.9 s 2.2 s
2.6 s 3.0 sChecks
2215 PASS 3 REVIEW 1 FIX
FHTTP CachingActionNo cache headersFIX
HTTP Caching
ActionNo cache headers
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.
BJS Execution Cost506ms total JS executionREVIEW
JS Execution Cost
506ms total JS execution
506ms total JS execution
Info::
https://story-viewer.online/: 144ms CPU time
Info::
https://story-viewer.online/_next/static/chunks/67...: 122ms CPU time
Info::
https://story-viewer.online/_next/static/chunks/87...: 120ms CPU time
Info::
Unattributable: 61ms CPU time
Info::
https://scripts.clarity.ms/0.8.69/clarity.js: 59ms CPU time
Info::
Third-party scripts: 59ms (12% of total)
Main Thread Breakdown
Script Evaluation 51% Other 22% Style & Layout 18% Script Parsing & Compilation 3%
| Script | Total | Scripting | Parse/Compile | Party |
|---|---|---|---|---|
| https://story-viewer.online/ | 144ms | 5ms | 3ms | 1st |
| https://story-viewer.online/_next/static/chunks/6733-006ecefe29f53e21.js | 122ms | 80ms | 3ms | 1st |
| https://story-viewer.online/_next/static/chunks/8724-0e5a48a498da935b.js | 120ms | 115ms | 3ms | 1st |
| Unattributable | 61ms | 3ms | 0ms | 1st |
| https://scripts.clarity.ms/0.8.69/clarity.js | 59ms | 52ms | 2ms | 3rd |
BMain HTML Cache-ControlNo Cache-Control header on main HTML responseREVIEW
Main HTML Cache-Control
No Cache-Control header on main HTML response
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.
BServer-Timing ObservabilityNo Server-Timing header foundREVIEW
Server-Timing Observability
No Server-Timing header found
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 Budget300 KB transferred, 27 requestsPASS
Page Weight Budget
300 KB transferred, 27 requests
300 KB transferred, 27 requests
Info::
Page weighs 963 KB (300 KB transferred)
Info::
27 HTTP requests
Info::
Estimated 0.06 g CO2 per page load
300 KB transferred
27 requests
0.06 g CO2 per page load
JavaScript 229.8 KiB 77%
Fonts 31.1 KiB 10%
HTML 19.5 KiB 7%
CSS 16.3 KiB 5%
Other 1.7 KiB 1%
Other 814 B 0%
Other 566 B 0%
Other 0 B 0%
0 2.4 MB 4.9 MB
Under budget
A+Third-Party Impact10% third-party, 0 ms blockingPASS
Third-Party Impact
10% third-party, 0 ms blocking
10% third-party, 0 ms blocking
Info::
Third-party code accounts for 10% of page weight (30.9 KiB of 299.8 KiB)
Info::
Third-party blocking time is low (0 ms)
90%
First-party Third-party
A+Text CompressionAll text resources are compressedPASS
Text Compression
All text resources are compressed
All text resources are compressed
Info::
All text resources are compressed
All text resources are properly compressed.
A+Image OptimizationNo images on this pagePASS
Image Optimization
No images on this page
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 Loading1 fonts (31 KB)PASS
Font Loading
1 fonts (31 KB)
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)
558ca1a6aa3cb55e-s.p.woff2 woff2 swap
Size 31 KB
Load time 40 ms
Start 191 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 Bundles16 scripts, 23 KB unusedPASS
JS Bundles
16 scripts, 23 KB unused
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.
| Script | Size | Unused | Minified | Party |
|---|---|---|---|---|
| https://story-viewer.online/_next/static/chunks/6733-006ecefe29f53e21.js | 42 KB | 23 KB (54%) | ✓ | 1st |
| https://story-viewer.online/_next/static/chunks/7523-0eeadfca7ab75e1c.js | 9 KB | — | ✓ | 1st |
| https://story-viewer.online/_next/static/chunks/2554-3d26d28db2653ea6.js | 6 KB | — | ✓ | 1st |
| https://story-viewer.online/_next/static/chunks/main-app-e1a600ff156106ca.js | 1 KB | — | ✓ | 1st |
| https://story-viewer.online/_next/static/chunks/07f299c6-a37406445cb891f5.js | 54 KB | — | ✓ | 1st |
| https://story-viewer.online/_next/static/chunks/5892-b54ba5813f276bda.js | 4 KB | — | ✓ | 1st |
| https://story-viewer.online/_next/static/chunks/9801-f8b5bc5b43b4ee4e.js | 16 KB | — | ✓ | 1st |
| https://story-viewer.online/_next/static/chunks/8724-0e5a48a498da935b.js | 44 KB | — | ✓ | 1st |
| https://story-viewer.online/_next/static/chunks/app/%5Blocale%5D/page-19cf22cf7279ecd8.js | 11 KB | — | ✓ | 1st |
| https://story-viewer.online/_next/static/chunks/9578-e413bd6f8750b4ae.js | 6 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 CachingAll resources properly cachedPASS
Resource Caching
All resources properly cached
All resources properly cached
Info::
No caching issues found
All static resources have appropriate caching headers.
A+Critical Rendering PathNo render-blocking resourcesPASS
Critical Rendering Path
No render-blocking resources
No render-blocking resources
Info::
No render-blocking resources detected
A+Resource HintsNo optimization neededPASS
Resource Hints
No optimization needed
No optimization needed
Info::
No resource hint issues
A+HTTP/3 (QUIC)HTTP/3 advertised via Alt-SvcPASS
HTTP/3 (QUIC)
HTTP/3 advertised via Alt-Svc
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 CompressionDocument response uses brotliPASS
Document Compression
Document response uses brotli
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 PreloadLCP preload audit not availablePASS
LCP Image Preload
LCP preload audit not available
LCP preload audit not available
Info::
LCP image preload audit not available for this scan
A+Server Response Intelligence2 server-response signal(s) detectedPASS
Server Response Intelligence
2 server-response signal(s) detected
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 Inventory27 resources · 300 KB · 23 KB savings availablePASS
Page Weight Inventory
27 resources · 300 KB · 23 KB savings available
27 resources · 300 KB · 23 KB savings available
Info::
Within 1MB page-weight target
Got: 300 KB
Info::
7 third-party resources (10% of weight)
27 resources · 299.8 KiB · 7 third-party Within 1MB page-weight target
JavaScript 77% · 229.8 KiB
Font 10% · 31.1 KiB
Document 7% · 19.5 KiB
CSS 5% · 16.3 KiB
Other 1% · 2.3 KiB
Image 0% · 814 B
~22.5 KiB of savings available
Remove unused JavaScript: 22.5 KiB
| # | Resource | Type | Size | Cache | Unused | 3rd party | Issues |
|---|---|---|---|---|---|---|---|
| — | — | ||||||
| 27 resources | 299.8 KiB | ||||||
A+Green HostingWhether the site is served from green-energy infrastructurePASS
Green Hosting
Whether the site is served from green-energy infrastructure
Green Hosting
This site is hosted on green energy infrastructure
Provider: Cloudflare
Asset CompressionNo text asset hosts to measureINFO
Asset Compression
No text asset hosts to measure
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 Waterfall27 requests over 1940msINFO
Network Waterfall
27 requests over 1940ms
HTML JavaScript CSS Images Fonts XHR/Fetch Other
Third-Party Script CostPer-script blocking time, transfer cost, and cache headersINFO
Third-Party Script Cost
Per-script blocking time, transfer cost, and cache headers
12% of JavaScript execution is third-party
First-party Third-party 59ms · 25KB · €1/mo
| Script | Category | Execution | Transfer | Unused | Monthly Cost | Verdict |
|---|---|---|---|---|---|---|
Microsoft Clarity scripts.clarity.ms | Session Replay | 59ms | 25 KB | — | €1/mo | Optional |
Microsoft Clarity
Session Replay
Execution 59ms
Transfer 25 KB
Monthly Cost €1/mo
All checks on this page are automated. Results are estimates - run targeted manual reviews when the score affects a release decision.