kosik.cz website review

About 533 KiB of JavaScript is downloaded but never used on this page. Google estimates it would make the page about 1.7 s faster on a phone.

Your mobile performance score is 22 (desktop: 57). Under 50 is Google's “poor” band: many phone visitors leave before the page is usable.

A phone's processor spends 5.6 s on main-thread work while loading, 3.1 s of it running JavaScript. Above 2 s, taps and scrolls feel sluggish.

The page has 4,357 HTML elements. Above 1,500, rendering and every interaction get slower on phones.

7 third-party services load with your homepage (Google Tag Manager, Constructor.io and growthbook.io and others), adding 605 KiB and 982 ms of main-thread time.

Google Tag Manager costs a phone 938 ms of main-thread work and 530 KiB of downloads while your page loads. Loading it after the page is usable, or only on the pages that need it, takes that off the critical path.

14 files block the first paint until they finish downloading. Deferring or inlining them could save about 650 ms.

2 images could be 63 KiB smaller with modern formats (WebP or AVIF) and sizes that fit a phone screen. Google estimates it would make the page about 550 ms faster on a phone.

19 long tasks block the main thread while loading, the longest for 482 ms. During a long task the page ignores taps.

1 file is served with short cache lifetimes, so returning visitors download them again (61 KiB).

Desktop scores 57 but mobile only 22. A gap that wide usually means heavy scripts and images that hit phones hardest.

Polyfills for old browsers add 8 KiB JavaScript that modern phones do not need.

Critical files load one after another instead of in parallel (3 chains). Preconnecting to key origins and preloading the hero image shortens the chain.

Scripts make the browser recalculate the layout repeatedly while the page loads, which wastes processor time on phones.

Real Chrome users on phones do not pass Google's Core Web Vitals on this page (28-day field data from the Chrome UX Report (opens in a new tab)). Google uses this in ranking.

Real visitors wait 617 ms for the page to respond to a tap (75th percentile). Good is under 200 ms.

Your largest element takes 9.3 s to render on a phone. Google's threshold for “good” is 2.5 s. The largest element is the image.

The page becomes fully interactive after 15.3 s. Good is under 3.8 s.

The first text or image appears after 5.2 s on a phone. Good is under 1.8 s.

Visually, the page fills in at 9.1 s (Speed Index). Good is under 3.4 s.

Scripts block taps and scrolling for 1.3 s in total while the page loads. Good is under 200 ms.

Real visitors wait 3.6 s for the largest content to appear (75th percentile). Good is under 2.5 s.

For real visitors the layout shifts by 0.21 (75th percentile). Good is under 0.1.

Real visitors see the first content after 1.9 s (75th percentile). Good is under 1.8 s.

Real visitors wait 888 ms for your server to start answering (75th percentile). Good is under 800 ms.

The layout shifts by 0.213 while loading, so content jumps under the reader's thumb. Good is under 0.1.

1 image have no width and height attributes, so the layout jumps as each one loads.

Over the last 25 four-week periods to 2026-10-24, real Chrome visitors' tap response (inp) went from 509 ms to 506 ms at the 75th percentile (Chrome UX Report (opens in a new tab) history).

Over the last 25 four-week periods to 2026-10-24, real Chrome visitors' largest content (lcp) went from 3.5 s to 3.6 s at the 75th percentile (Chrome UX Report (opens in a new tab) history).

Your homepage downloads 2.2 MB in 181 requests on a phone: scripts 1.4 MB (96), images 615 KiB (39) and other files 99 KiB (27). Under 2 MB keeps phones on slow connections fast.

By the Sustainable Web Design model, a visit to your homepage emits about 0.63 g of CO₂e: 75.6 kg a year at 10,000 visits a month. It scales with page weight, so every byte cut lowers it.

Images must have alternative text: 6 elements on the page fail this check, rated critical by axe-core.

1 button has no accessible name, so screen readers announce just “button”.

8 text elements don't have enough contrast against the background to read easily, especially outdoors on a phone.

Elements must only use permitted ARIA attributes: 1 element on the page fails this check, rated serious by axe-core.

All page content should be contained by landmarks: 72 elements on the page fail this check, rated moderate by axe-core.

24 tap targets are too small or too close together to hit reliably with a finger.

11 visible links have no text or label, so screen readers cannot say where they go.

There is no <h1>, so neither visitors nor Google get a clear main headline.

No structured data (JSON-LD), so Google can't show rich results such as your logo, ratings or FAQs.

No canonical URL, so duplicate versions of the homepage (with or without www, with tracking parameters) can split ranking signals.

The homepage links to only 0 pages on your own site, so visitors and crawlers find few routes into the rest of it.

A phone browser shows 495 words, but the HTML your server sends has only 0. GPTBot, ClaudeBot and PerplexityBot read that HTML without running JavaScript, so they see an almost empty page. Server-side rendering or pre-rendering fixes it.

There is no Organization (or LocalBusiness) JSON-LD, so search engines and AI assistants have no machine-readable facts about who runs the site: its name, logo, profiles and contact details.

Large scripts ship without source maps.

On a phone, there is no call to action on the first screen: visitors have to scroll to find out what to do next.

We found no call-to-action buttons or links (such as “Book a demo” or “Get a quote”) anywhere on the homepage.

No testimonials, customer logos, ratings or customer counts on the homepage: nothing tells a new visitor that others already trust you.

No analytics or tag manager detected in the HTML, so you can't measure whether any of these fixes work.

No phone number or email link on the homepage, so ready-to-buy visitors have one fewer way to reach you.

There is no form on the homepage, so every lead has to click through to another page first.

No guarantee or risk reducer (money-back, free trial, no credit card) is mentioned, which is often what tips a hesitant visitor.

The homepage carries about 495 words of visible text.

Before a visitor clicks anything, the page loads Google Tag Manager (measured from a US location before any click). No consent tool was detected. Visitors from the EU, UK and several US states must be asked first.

Opening the homepage sets 2 cookies (measured from a US location before any click).

No known cookie consent tool loads with the page. Some sites build their own banner, and some only show one to visitors from the EU.

Loading the homepage contacts 4 hosts run by other companies (fonts, scripts, analytics, ads), each of which sees the visitor's IP address.