vaillant.de website review

Your mobile performance score is 76. Pages that score under 90 lose visitors before the first paint.

4 files are served with short cache lifetimes, so returning visitors download them again (183 KiB).

11 long tasks block the main thread while loading, the longest for 321 ms. During a long task the page ignores taps.

consentmanager.net costs a phone 255 ms of main-thread work and 135 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.

A phone's processor spends 2.2 s on main-thread work while loading, 1.1 s of it running JavaScript. Above 2 s, taps and scrolls feel sluggish.

2 third-party services load with your homepage (consentmanager.net and Optimizely), adding 265 KiB and 255 ms of main-thread time.

1 file blocks the first paint until they finish downloading. Deferring or inlining it could save about 250 ms.

About 181 KiB of JavaScript is downloaded but never used on this page.

6 images could be 142 KiB smaller with modern formats (WebP or AVIF) and sizes that fit a phone screen.

About 22 KiB of CSS is downloaded but never applied on this page.

Polyfills for old browsers add 14 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.

2 KiB could be saved by minifying CSS.

The page becomes fully interactive after 7.0 s. Good is under 3.8 s.

Scripts block taps and scrolling for 514 ms in total while the page loads. Good is under 200 ms.

Your largest element takes 3.5 s to render on a phone. Google's threshold for “good” is 2.5 s. The largest element is the image “Zwei Vaillant Wärmepumpen stehen vor einem beigen Hintergru…”.

Visually, the page fills in at 3.9 s (Speed Index). Good is under 3.4 s.

Over the last 25 four-week periods to 2026-10-31, real Chrome visitors' tap response (inp) went from 145 ms to 147 ms at the 75th percentile (Chrome UX Report (opens in a new tab) history).

Over the last 25 four-week periods to 2026-10-31, real Chrome visitors' largest content (lcp) went from 1.4 s to 1.5 s at the 75th percentile (Chrome UX Report (opens in a new tab) history).

Your homepage downloads 2.1 MB in 74 requests on a phone: images 967 KiB (26), scripts 781 KiB (31) and other files 201 KiB (9). Under 2 MB keeps phones on slow connections fast.

By the Sustainable Web Design model, a visit to your homepage emits about 0.60 g of CO₂e: 71.5 kg a year at 10,000 visits a month. It scales with page weight, so every byte cut lowers it.

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

Interactive controls must not be nested: 9 elements on the page fail this check, rated serious by axe-core.

Scrollable region must have keyboard access: 1 element on the page fails this check, rated serious by axe-core.

Landmarks should have a unique role or role/label/title (i.e. accessible name) combination: 1 element on the page fails this check, rated moderate by axe-core.

ARIA role should be appropriate for the element: 1 element on the page fails this check, rated minor by axe-core.

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

No Open Graph image (also missing: og:title, og:description), so links shared on LinkedIn, Slack or Facebook show no preview picture.

No twitter:card tag. X falls back to Open Graph, which is incomplete here.

The homepage links to 190 pages on vaillant.de and 14 external pages.

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.

There is no https://www.vaillant.de/llms.txt, a short Markdown guide to your key pages for AI tools (llmstxt.org). It is optional and few AI tools read it yet, so treat it as a cheap extra.

https://www.vaillant.de/ratgeber/technologie-verstehen, https://www.vaillant.de/ratgeber/technologie-verstehen/hybridheizung, https://www.vaillant.de/ratgeber/technologie-verstehen/gasheizung, https://www.vaillant.de/ratgeber/technologie-verstehen/brennwertheizung, https://www.vaillant.de/ratgeber/technologie-verstehen/photovoltaik and https://www.vaillant.de/ratgeber/technologie-verstehen/klimaanlage took over 3 s to send their HTML from our server.

We fetched 15 pages linked from your homepage (of 125 found) and read each the way a search engine does.

7 of 27 tappable elements near the top of the page are smaller than 24 px, hard to hit with a thumb.

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 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 1,159 words of visible text.

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

Loading the homepage contacts 3 hosts run by other companies (fonts, scripts, analytics, ads), each of which sees the visitor's IP address.