Main HTML response has no Content-Encoding (uncompressed)
The main HTML document is served without compression. The Text Compression section above lists the broader picture; for the main response specifically, even gzip would shave ~70-80% off most text payloads.
B
Main HTML Cache-Control
No Cache-Control header on main HTML response
REVIEW
No Cache-Control header on main HTML response
Info::
i
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::
i
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.
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+
Image Optimization
4 images, 0 KB saveable
PASS
4 images, 0 KB saveable
Info::
✓
All images are well-optimized
4images559 KB
0oversized-0 KB
0legacy format
0missing dimensionsCLS risk
A+
Font Loading
2 fonts (212 KB)
PASS
2 fonts (212 KB)
Info::
i
2 font(s) use font-display: swap (FOUT risk but functional)
Web fonts
2
212 KB total
Render-blocking
0
of 2
Dominant font-display
swap
Most common across fonts
Font loading timeline
TransferFOIT (block)FOUT (swap)
1GOXakOP6QP.woff2woff2swap
Size33 KB
Load time19 ms
Start502 ms
RiskFOUT — text flashes from fallback to web font
-pkMfchyeAZ.woff2woff2swap
Size179 KB
Load time23 ms
Start503 ms
RiskFOUT — 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 ~90 KB and ~180 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+
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+
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
1 server-response signal(s) detected
PASS
1 server-response signal(s) detected
Info::
i
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.
Network Waterfall
52 requests over 1700ms
INFO
HTML JavaScript CSS Images Fonts XHR/Fetch Other
Third-Party Script Cost
Per-script blocking time, transfer cost, and cache headers
INFO
92%of JavaScript execution is third-party
First-party Third-party674ms · 1085KB · $9/mo
Script
Category
Execution
Transfer
Unused
Monthly Cost
Verdict
static.cdninstagram.com
static.cdninstagram.com
Other
417ms
76 KB
44%
$6/mo
Costly
www.instagram.com
www.instagram.com
Other
105ms
100 KB
—
$1/mo
Optional
static.cdninstagram.com
static.cdninstagram.com
Other
86ms
722 KB
62%
$1/mo
Optional
static.cdninstagram.com
static.cdninstagram.com
Other
66ms
187 KB
43%
$1/mo
Optional
static.cdninstagram.com
Other
Costly
Execution417ms
Transfer76 KB
Unused44%
Monthly Cost$6/mo
www.instagram.com
Other
Optional
Execution105ms
Transfer100 KB
Monthly Cost$1/mo
static.cdninstagram.com
Other
Optional
Execution86ms
Transfer722 KB
Unused62%
Monthly Cost$1/mo
static.cdninstagram.com
Other
Optional
Execution66ms
Transfer187 KB
Unused43%
Monthly Cost$1/mo
These scripts may cost more than they're worth
static.cdninstagram.com adds 417ms and costs ~$6/month
92% 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
static.cdninstagram.com takes 417ms 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
62% of static.cdninstagram.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.
375 ms
750 ms
1.1 s
1.5 s