https://instagramstoryviewer.cc
Performance
· 22 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.SCORE
91
GRADE
A
FIX
1
REVIEW
6
PASS
12
INFO
3
Performance-focused optimization plan with CWV assessment, top offenders, and time estimates
100
95
81
100
First Contentful Paint First Contentful Paint — how long until the browser renders the first piece of content. Under 1.8s is good.
452 ms
Largest Contentful Paint Largest Contentful Paint — how long until the largest visible element loads. Under 2.5s is good.
590 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.
492 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.
592 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
2212 PASS 6 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 Bundles9 scripts, 98 KB unusedREVIEW
JS Bundles
9 scripts, 98 KB unused
9 scripts, 98 KB unused
Warning::
https://www.googletagmanager.com/gtag/js?id=G-LE67...: 72 KB unused (41%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://instagramstoryviewer.cc/assets/framework-D...: 26 KB unused (45%)
Consider code splitting or tree shaking to reduce unused code.
Info::
Total unused JavaScript: 98 KB
98 KB unused JavaScript
Downloaded but never executed on this page.
| Script | Size | Unused | Minified | Party |
|---|---|---|---|---|
| https://www.googletagmanager.com/gtag/js?id=G-LE67EY6MM1 | 176 KB | 72 KB (41%) | ✓ | 3rd |
| https://instagramstoryviewer.cc/assets/framework-DjPHiq1u.js | 58 KB | 26 KB (45%) | ✓ | 1st |
| https://instagramstoryviewer.cc/assets/layout-segment-context-D5cMo-KD.js | 0 KB | — | ✓ | 1st |
| https://instagramstoryviewer.cc/assets/rolldown-runtime-S-ySWqyJ.js | 0 KB | — | ✓ | 1st |
| https://instagramstoryviewer.cc/assets/index-r7lsyBqO.js | 24 KB | — | ✓ | 1st |
| https://instagramstoryviewer.cc/assets/script-BCQCzhfo.js | 1 KB | — | ✓ | 1st |
| https://instagramstoryviewer.cc/assets/page-D_Vwn2-Q.js | 4 KB | — | ✓ | 1st |
| https://instagramstoryviewer.cc/assets/link-vHCogT2p.js | 4 KB | — | ✓ | 1st |
| https://instagramstoryviewer.cc/cdn-cgi/challenge-platform/h/g/scripts/jsd/4df4a60fa397/main.js? | 13 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
BHTTP/3 (QUIC)HTTP/3 not advertisedREVIEW
HTTP/3 (QUIC)
HTTP/3 not advertised
HTTP/3 not advertised
Info::
HTTP/3 (QUIC) is not advertised
HTTP/3 isn't advertised via Alt-Svc and the worker didn't negotiate h3. HTTP/3 reduces handshake latency (1-RTT instead of 2-3 RTTs) and is more resilient on lossy connections. Most modern CDNs (Cloudflare, Fastly, AWS CloudFront, Google Cloud CDN) support HTTP/3 with a single config switch -- consider enabling for mobile-heavy workloads.
BDocument CompressionDocument response uses gzip; brotli would be ~20% smallerREVIEW
Document Compression
Document response uses gzip; brotli would be ~20% smaller
Document response uses gzip; brotli would be ~20% smaller
Info::
Main HTML response uses gzip (brotli would be ~20% smaller)
All current browsers support brotli. Most CDNs (Cloudflare, Fastly, AWS CloudFront, Vercel, Netlify) can switch from gzip to brotli with a single config flag. Origin servers (nginx, Apache) need a brotli module compiled in -- nginx-brotli or Apache mod_brotli.
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.
CGreen HostingActionWhether the site is served from green-energy infrastructureREVIEW
Green Hosting
ActionWhether the site is served from green-energy infrastructure
Green Hosting
No green hosting detected
A+Page Weight Budget447 KB transferred, 28 requestsPASS
Page Weight Budget
447 KB transferred, 28 requests
447 KB transferred, 28 requests
Info::
Page weighs 1.0 MB (447 KB transferred)
Info::
28 HTTP requests
Info::
Estimated 0.09 g CO2 per page load
447 KB transferred
28 requests
0.09 g CO2 per page load
JavaScript 280.8 KiB 63%
Fonts 144.1 KiB 32%
HTML 8.3 KiB 2%
CSS 5.9 KiB 1%
Other 5.4 KiB 1%
Other 1.3 KiB 0%
Other 877 B 0%
0 2.4 MB 4.9 MB
Under budget
AThird-Party Impact39% third-party, 0 ms blockingPASS
Third-Party Impact
39% third-party, 0 ms blocking
39% third-party, 0 ms blocking
Info::
Third-party code accounts for 39% of page weight (176.2 KiB of 446.6 KiB)
Info::
Third-party blocking time is low (0 ms)
61%
39%
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+JS Execution Cost233ms total JS executionPASS
JS Execution Cost
233ms total JS execution
233ms total JS execution
Info::
https://instagramstoryviewer.cc/: 100ms CPU time
Info::
https://instagramstoryviewer.cc/cdn-cgi/challenge-...: 75ms CPU time
Info::
https://www.googletagmanager.com/gtag/js?id=G-LE67...: 58ms CPU time
Info::
Third-party scripts: 58ms (25% of total)
Main Thread Breakdown
Script Evaluation 53% Style & Layout 26% Other 14% Script Parsing & Compilation 4%
| Script | Total | Scripting | Parse/Compile | Party |
|---|---|---|---|---|
| https://instagramstoryviewer.cc/ | 100ms | 11ms | 1ms | 1st |
| https://instagramstoryviewer.cc/cdn-cgi/challenge-platform/scripts/jsd/main.js | 75ms | 71ms | 1ms | 1st |
| https://www.googletagmanager.com/gtag/js?id=G-LE67EY6MM1 | 58ms | 47ms | 11ms | 3rd |
A+Font Loading11 fonts (144 KB)PASS
Font Loading
11 fonts (144 KB)
11 fonts (144 KB)
Info::
11 font(s) use font-display: swap (FOUT risk but functional)
Web fonts
11
144 KB total
Render-blocking
0
of 11
Dominant font-display
swap
Most common across fonts
Font loading timeline
Transfer FOIT (block) FOUT (swap)
geist-ff2310f5.woff2 woff2 swap
Size 7 KB
Load time 161 ms
Start 129 ms
Risk FOUT — text flashes from fallback to web font
geist-875ccdd4.woff2 woff2 swap
Size 15 KB
Load time 159 ms
Start 130 ms
Risk FOUT — text flashes from fallback to web font
geist-52306abf.woff2 woff2 swap
Size 8 KB
Load time 181 ms
Start 130 ms
Risk FOUT — text flashes from fallback to web font
geist-001175b1.woff2 woff2 swap
Size 16 KB
Load time 139 ms
Start 130 ms
Risk FOUT — text flashes from fallback to web font
geist-98bbbccb.woff2 woff2 swap
Size 29 KB
Load time 162 ms
Start 131 ms
Risk FOUT — text flashes from fallback to web font
geist-mono-f6b33328.woff2 woff2 swap
Size 6 KB
Load time 163 ms
Start 131 ms
Risk FOUT — text flashes from fallback to web font
geist-mono-44e03052.woff2 woff2 swap
Size 13 KB
Load time 163 ms
Start 131 ms
Risk FOUT — text flashes from fallback to web font
geist-mono-0638449e.woff2 woff2 swap
Size 6 KB
Load time 173 ms
Start 132 ms
Risk FOUT — text flashes from fallback to web font
geist-mono-971fb274.woff2 woff2 swap
Size 8 KB
Load time 174 ms
Start 132 ms
Risk FOUT — text flashes from fallback to web font
geist-mono-44745446.woff2 woff2 swap
Size 14 KB
Load time 144 ms
Start 132 ms
Risk FOUT — text flashes from fallback to web font
geist-mono-013b2f2f.woff2 woff2 swap
Size 23 KB
Load time 179 ms
Start 132 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+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+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, Accept, Next-Router-State-Tree, Next-Router-Prefetch, Next-Router-Segment-P...
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 Inventory28 resources · 447 KB · 98 KB savings availablePASS
Page Weight Inventory
28 resources · 447 KB · 98 KB savings available
28 resources · 447 KB · 98 KB savings available
Info::
Within 1MB page-weight target
Got: 447 KB
Info::
~98 KB of savings available
Info::
2 third-party resources (39% of weight)
28 resources · 446.6 KiB · 2 third-party Within 1MB page-weight target
JavaScript 63% · 280.8 KiB
Font 32% · 144.1 KiB
Document 2% · 8.3 KiB
Other 2% · 7.1 KiB
CSS 1% · 5.9 KiB
Image 0% · 478 B
~98.1 KiB of savings available
Remove unused JavaScript: 98.1 KiB
| # | Resource | Type | Size | Cache | Unused | 3rd party | Issues |
|---|---|---|---|---|---|---|---|
| — | — | ||||||
| 28 resources | 446.6 KiB | ||||||
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 Waterfall28 requests over 759msINFO
Network Waterfall
28 requests over 759ms
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
25% of JavaScript execution is third-party
First-party Third-party 58ms · 176KB · €1/mo
| Script | Category | Execution | Transfer | Unused | Monthly Cost | Verdict |
|---|---|---|---|---|---|---|
Google Tag Manager www.googletagmanager.com | Tag Manager | 58ms | 176 KB | 41% | €1/mo | Optional |
Google Tag Manager
Tag Manager
Execution 58ms
Transfer 176 KB
Unused 41%
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.