Skip to content
https://amista.cz

Performance

· 27 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
89
GRADE
B
FIX
2
REVIEW
6
PASS
16
INFO
3

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

Mobile Desktop
82
Performance Overall performance score (0–100) based on Core Web Vitals and other metrics. 90+ is good.
96
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.
83
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.

3.00 s

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

3.52 s

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.

4.96 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.

3.55 s

Page Load Progression

594 ms
1.2 s
1.8 s
2.4 s
3.0 s
3.6 s
4.2 s
4.8 s
Checks
27
16 PASS 6 REVIEW 2 FIX
D
Third-Party Impact
Action
100% third-party, 0 ms blocking
FIX
100% third-party, 0 ms blocking
Warning::
Third-party code accounts for 100% of page weight (716.1 KiB of 716.7 KiB)
Info::
Third-party blocking time is low (0 ms)
100%
First-party Third-party
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: no-store, no-cache, must-revalidate
Info::
No ETag or Last-Modified header
Conditional requests (304 Not Modified) are not possible without validators.
Cache-Control

no-store, no-cache, must-revalidate

DirectiveValueMeaning
no-store—Never cache this response
no-cache—Cache but always revalidate first
must-revalidate—Must recheck with server after expiry
C
JS Execution Cost
Action
1297ms total JS execution
REVIEW
1297ms total JS execution
Warning::
https://www.amista.cz/: 949ms CPU time
Info::
https://www.amista.cz/js/libs/jquery-3.5.1.min.js: 190ms CPU time
Info::
Unattributable: 158ms CPU time
Warning::
Third-party scripts: 1139ms (88% of total)

Main Thread Breakdown

Other 55% Style & Layout 26% Script Evaluation 9% Rendering 4%
ScriptTotalScriptingParse/CompileParty
https://www.amista.cz/949ms10ms4ms3rd
https://www.amista.cz/js/libs/jquery-3.5.1.min.js190ms69ms17ms3rd
Unattributable158ms5ms0ms1st
B
HTTP/3 (QUIC)
HTTP/3 not advertised
REVIEW
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.
C
Document Compression
Action
Document response served uncompressed
REVIEW
Document response served uncompressed
Info::
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
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.
B
JavaScript Blocking
1 JS blocking issue(s) detected
REVIEW
1 JS blocking issue(s) detected
Warning::
8 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.
C
Green Hosting
Action
Whether the site is served from green-energy infrastructure
REVIEW

Green Hosting

No green hosting detected

A
Page Weight Budget
717 KB transferred, 22 requests
PASS
717 KB transferred, 22 requests
Info::
Page weighs 1.0 MB (717 KB transferred)
Info::
22 HTTP requests
Info::
Estimated 0.15 g CO2 per page load
717 KB / 2.4 MB budget
717 KB transferred
22 requests
0.15 g CO2 per page load
Images 541.2 KiB 76%
JavaScript 71.9 KiB 10%
Fonts 53.5 KiB 7%
CSS 30.1 KiB 4%
HTML 12.2 KiB 2%
Other 4.4 KiB 1%
Other 2.6 KiB 0%
Other 727 B 0%
0 2.4 MB 4.9 MB
Under budget
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
2 images, 0 KB saveable
PASS
2 images, 0 KB saveable
Warning::
is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
2 images 541 KB
0 oversized -0 KB
1 legacy format
1 missing dimensions CLS risk

Set explicit width and height to prevent CLS.

Why this matters

Performance issues directly impact user engagement and conversion rates.

A+
Font Loading
3 fonts (53 KB)
PASS
3 fonts (53 KB)
Info::
3 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

3

53 KB total

Render-blocking

0

of 3

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 FCP 3.0 s LCP 3.5 shttps://www.amista.cz/fonts/Manrope-variable.woff2?ver=3.0.0Manrope-variable.woff2 https://www.amista.cz/fonts/Manrope-variable.woff2?ver=3.0.0 — 22.3 KiB — 37 ms — font-display: swaphttps://www.amista.cz/fonts/ITC-AvantGardePro-500.woff2?ver=1.0.0ITC-AvantGardePro-500.w... https://www.amista.cz/fonts/ITC-AvantGardePro-500.woff2?ver=1.0.0 — 16.9 KiB — 38 ms — font-display: swaphttps://www.amista.cz/fonts/Manrope-variable-ext.woff2?ver=3.0.0Manrope-variable-ext.woff2 https://www.amista.cz/fonts/Manrope-variable-ext.woff2?ver=3.0.0 — 14.3 KiB — 37 ms — font-display: swap
Manrope-variable.woff2 woff2 swap
Size 22 KB
Load time 37 ms
Start 475 ms
Risk FOUT — text flashes from fallback to web font
ITC-AvantGardePro-500.w... woff2 swap
Size 17 KB
Load time 38 ms
Start 476 ms
Risk FOUT — text flashes from fallback to web font
Manrope-variable-ext.woff2 woff2 swap
Size 14 KB
Load time 37 ms
Start 502 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
8 scripts, 0 KB unused
PASS
8 scripts, 0 KB unused
0 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://www.amista.cz/js/libs/jquery-3.5.1.min.js31 KB—✓3rd
https://www.amista.cz/js/libs/focus-visible-5.0.0.min.js1 KB—✓3rd
https://www.amista.cz/js/script.js?timestamp=16127864082 KB—✓3rd
https://shared.animato.cz/ruzne.js2 KB—✓3rd
https://shared.animato.cz/jquery.forms.js8 KB—✓3rd
https://shared.animato.cz/imgs_system/eshop/checkbox/checkbox.js1 KB—✓3rd
https://shared.animato.cz/imgs_system/photoswipe/bundle.js16 KB—✓3rd
https://cookies-consent-p5.pria.cz/amista-index.js11 KB—✓3rd
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
Asset Compression
1 of 1 asset host still on gzip
PASS
1 of 1 asset host still on gzip
Info::
shared.animato.cz serves assets with gzip; brotli would be ~20% smaller (assets: 7)
Every current browser accepts brotli. On a CDN this is a per-pull-zone toggle (Cloudflare, Fastly, CloudFront, CDN77, Bunny all expose it); on an origin it needs the brotli module (nginx-brotli, Apache mod_brotli). The saving lands on the assets this host serves, not on the HTML document -- the document's own encoding is reported separately.
Got: shared.animato.cz (text/css)
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+
Main HTML Cache-Control
Main HTML uses no-store -- correct for sensitive/dynamic content
PASS
Main HTML uses no-store -- correct for sensitive/dynamic content
Info::
Main HTML uses no-store -- correct for sensitive/dynamic content
Got: no-store, no-cache, must-revalidate
A+
Server Response Intelligence
1 server-response signal(s) detected
PASS
1 server-response signal(s) detected
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
22 resources · 717 KB · 0 KB savings available
PASS
22 resources · 717 KB · 0 KB savings available
Info::
Within 1MB page-weight target
Got: 717 KB
Warning::
21 third-party resources (100% of weight)
Info::
1 resources over 200KB
22 resources · 716.7 KiB · 21 third-party Within 1MB page-weight target
Image 76% · 543.3 KiB
JavaScript 10% · 71.9 KiB
Font 7% · 53.5 KiB
CSS 5% · 34.5 KiB
Document 2% · 12.7 KiB
Other 0% · 727 B
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
CSS Performance Depth
1 CSS depth issue(s) detected
PASS
1 CSS depth issue(s) detected
Warning::
5 render-blocking stylesheet(s) -- recommended: <=3
Each `<link rel="stylesheet">` without a non-blocking `media` attribute holds up the first paint. Browsers download all of them before painting any content. Consolidate into 1-2 critical-path stylesheets; defer non-critical CSS via `<link rel="stylesheet" media="print" onload="this.media='all'">` or via the loadCSS pattern; inline above-the-fold CSS in `<style>` to short-circuit the request entirely.
Network Waterfall
22 requests over 1626ms
INFO
0 ms 1.0 s 2.0 s 3.0 s FCP 3.0 s LCP 3.5 shttps://amista.cz// https://amista.cz/ — 301 — 589 B — 112 ms — http/1.1https://www.amista.cz/www.amista.cz/ https://www.amista.cz/ — 200 — 12.2 KiB — 146 ms — http/1.1https://www.amista.cz/normalize.css?timestamp=1614677555www.amista.cz/normalize.css?timesta... https://www.amista.cz/normalize.css?timestamp=1614677555 — 200 — 1.2 KiB — 38 ms — http/1.1https://www.amista.cz/layout.css?timestamp=1614677556www.amista.cz/layout.css?timestamp=... https://www.amista.cz/layout.css?timestamp=1614677556 — 200 — 4.5 KiB — 74 ms — http/1.1https://www.amista.cz/styles.css?timestamp=1771252483www.amista.cz/styles.css?timestamp=... https://www.amista.cz/styles.css?timestamp=1771252483 — 200 — 12.4 KiB — 140 ms — http/1.1https://www.amista.cz/utilities.css?timestamp=1614677557www.amista.cz/utilities.css?timesta... https://www.amista.cz/utilities.css?timestamp=1614677557 — 200 — 9.3 KiB — 111 ms — http/1.1https://www.amista.cz/js/libs/jquery-3.5.1.min.jswww.amista.cz/js/libs/jquery-3.5.1.... https://www.amista.cz/js/libs/jquery-3.5.1.min.js — 200 — 30.5 KiB — 142 ms — http/1.1https://www.amista.cz/js/libs/focus-visible-5.0.0.min.jswww.amista.cz/js/libs/focus-visible... https://www.amista.cz/js/libs/focus-visible-5.0.0.min.js — 200 — 1.3 KiB — 107 ms — http/1.1https://www.amista.cz/js/script.js?timestamp=1612786408www.amista.cz/js/script.js?timestam... https://www.amista.cz/js/script.js?timestamp=1612786408 — 200 — 1.9 KiB — 106 ms — http/1.1https://shared.animato.cz/ruzne.jsshared.animato.cz/ruzne.js https://shared.animato.cz/ruzne.js — 200 — 2.1 KiB — 196 ms — h2https://shared.animato.cz/jquery.forms.jsshared.animato.cz/jquery.forms.js https://shared.animato.cz/jquery.forms.js — 200 — 8.2 KiB — 195 ms — h2https://shared.animato.cz/imgs_system/eshop/checkbox/checkbox.jsshared.animato.cz/imgs_system/eshop... https://shared.animato.cz/imgs_system/eshop/checkbox/checkbox.js — 200 — 638 B — 195 ms — h2https://shared.animato.cz/imgs_system/photoswipe/bundle.jsshared.animato.cz/imgs_system/photo... https://shared.animato.cz/imgs_system/photoswipe/bundle.js — 200 — 16.1 KiB — 186 ms — h2https://www.amista.cz/site.webmanifestwww.amista.cz/site.webmanifest https://www.amista.cz/site.webmanifest — 200 — 727 B — 106 ms — http/1.1https://cookies-consent-p5.pria.cz/amista-index.jscookies-consent-p5.pria.cz/amista-i... https://cookies-consent-p5.pria.cz/amista-index.js — 200 — 11.2 KiB — 184 ms — http/1.1https://www.amista.cz/fonts/Manrope-variable.woff2?ver=3.0.0www.amista.cz/fonts/Manrope-variabl... https://www.amista.cz/fonts/Manrope-variable.woff2?ver=3.0.0 — 200 — 22.3 KiB — 37 ms — http/1.1https://www.amista.cz/fonts/ITC-AvantGardePro-500.woff2?ver=1.0.0www.amista.cz/fonts/ITC-AvantGardeP... https://www.amista.cz/fonts/ITC-AvantGardePro-500.woff2?ver=1.0.0 — 200 — 16.9 KiB — 38 ms — http/1.1https://www.amista.cz/fonts/Manrope-variable-ext.woff2?ver=3.0.0www.amista.cz/fonts/Manrope-variabl... https://www.amista.cz/fonts/Manrope-variable-ext.woff2?ver=3.0.0 — 200 — 14.3 KiB — 37 ms — http/1.1https://shared.animato.cz/imgs_system/photoswipe/default-skin/bundle.cssshared.animato.cz/imgs_system/photo... https://shared.animato.cz/imgs_system/photoswipe/default-skin/bundle.css — 200 — 2.7 KiB — 38 ms — h2https://cookies-consent-p5.pria.cz/cookieconsent.csscookies-consent-p5.pria.cz/cookieco... https://cookies-consent-p5.pria.cz/cookieconsent.css — 200 — 4.4 KiB — 104 ms — http/1.1https://www.amista.cz/favicon-32x32.pngwww.amista.cz/favicon-32x32.png https://www.amista.cz/favicon-32x32.png — 200 — 2.0 KiB — 36 ms — http/1.1https://www.amista.cz/files/thumbs/stranka-0.3764677488.pngwww.amista.cz/files/thumbs/stranka-... https://www.amista.cz/files/thumbs/stranka-0.3764677488.png — 200 — 541.2 KiB — 206 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
88% of JavaScript execution is third-party
First-party Third-party 1139ms · 43KB · Kč141/mo
www.amista.cz
Other
Costly
Execution 949ms
Transfer 12 KB
Monthly Cost Kč117/mo
www.amista.cz
Other
Optional
Execution 190ms
Transfer 31 KB
Monthly Cost Kč23/mo

These scripts may cost more than they're worth

  • www.amista.cz adds 949ms and costs ~Kč117/month

88% 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

www.amista.cz takes 949ms 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

Image Optimization
8 images, 541 KB total, 491 KB wasted
INFO

Image Optimization Audit

Total Images

8

Total Size

541 KB

Oversized

1

Wasted

491 KB

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

Send Feedback