The first impression counts
Imagine someone clicks on a link to your site. The decision is made within 1-2 seconds: do I stay or do I go back to the search results? A slow page looks unprofessional and subliminally conveys the feeling that the product or service behind it is not of high quality either. Every second counts: In the digital world, the speed of a website often determines whether a visitor stays or leaves immediately. Studies show that a delay in loading time of just one second can reduce the conversion rate by several percent. And it's not just users who react sensitively - search engines such as Google also evaluate the performance of a website.
Measure Page Spee with the Google Core Web Vitals
To make the quality of a website measurable from the user's point of view, Google has developed the Core Web Vitals introduced. These metrics are now an integral part of search engine evaluation and therefore a key factor for visibility and success on the web. The Core Web Vitals reflect what users expect the most: speed, responsiveness and stability. If these expectations are not met, users bounce - and this effect is directly reflected in conversions, leads or sales.
Influence on SEO and rankings
Core Web Vitals have been an official Google ranking factor since 2021. This means that websites with good values have a better chance of achieving top rankings. According to the latest research results, however, the influence of CWVs is less than 10%.
Since 2024, the following 5 metrics have all specified an ideal value.
1 - Largest Contentful Paint (LCP)
Wichtigster Facktor. Er misst, wie schnell das grösste sichtbare Element (z. B. Bild oder Textblock) geladen wird. Die häufigsten Probleme sind hier zu grosse Bilder, langsames Hosting, fehlendes Caching oder Render-Blocking-Skripte (unoptimiertes CSS/JS). Der Zielwert sollte unter 2,5 Sekunden liegen.
2 - Interaction to Next Paint (INP)
Measures the response time of a page to user interactions (clicks, taps, keystrokes). Most problems arise here with heavy JavaScript (many event listeners, tracking, unoptimized frameworks). The target value should be less than 200 milliseconds lie
3 - Cumulative Layout Shift (CLS)
Measures how stable the layout remains while content is loading. Jumping buttons or shifted texts frustrate users. Happens due to advertising or images without correct dimensions in case of incorrect rsponsive implementation. Is easy to fix. The target value should be unter 0,1 lie
4 - First Contentful Paint (FCP)
How quickly does the first visible content appear on the screen? Closely linked to CSS/JS blocking and fonts. The target value should be under 1.8s lie
5 - Time to First Byte (TTFB)
How quickly does the server deliver the first data to the browser? This is usually a CDN or hosting issue. The target value should be under 0.8s lie
The perceived speed
As important as the Core Web Vitals are, they do not always tell the whole truth. The metrics are based on standardized measurement methods and provide technical guidance. However, how fast or slow a website actually is (i.e. how it is perceived by the person behind the screen) can vary significantly. Such differences are often caused by technical conditions that have very different effects in the laboratory (e.g. Lighthouse test) or on individual users. Here we list the most important reasons why measured web vitals values and perceived speed can differ:
1 - Caching
Everything is freshly loaded on the first call - fonts, CSS, images. The lab measurement always simulates a first call. In reality, however, users visit a page several times. On repeated visits, many files are already in the browser cache, so that the page appears subjectively much faster.
2 - Content Delivery Networks (CDNs)
When measuring, tools often access the page from a data center that is not necessarily close to the nearest CDN pop. This makes loading times appear longer than they actually are. In practice, however, users in geographical proximity to a CDN node can experience extremely much faster loading times.
3 - A/B tests and third-party scripts
Marketing or tracking scripts can have a greater impact on performance in the lab setup than in real operation. Users often do not notice that additional requests are running in the background when it is perfectly integrated.
4 - Lazy loading and placeholders
From the user's point of view, a page appears to be "immediately there" when critical content is visible. Technically, however, it is still loading (e.g. images outside the viewport). This feels faster than the metrics measure.
5 - Devices and networks
A high-end notebook renders JavaScript and animations smoothly, while an older smartphone falters - with identical measured values. Different latencies, mobile communications vs. fiber optics, 3G vs. 5G. The tools simulate certain bandwidths, but the reality often differs.
6 - Ad blockers & extensions
Many real users have ad blockers or other extensions installed - this speeds up or slows down their perceived loading time.
7 - Psychology & perception
Users often perceive a page as "fully loaded" as soon as navigation, text and images are visible. However, the metrics also measure when all scripts are ready or how quickly the page reacts to interactions - which is sometimes not so strongly reflected in the feeling.
The truth lies somewhere in the middle
At Gridonic, we use a simple formula that takes all three performance variables into account.
Perceived speed: The feeling that a website leaves a real user with
Measured Speed: Core Web Vitals, how they are measured.
Hardware Speed: The feeling on an older device.
Sources:
https://www.conductor.com/academy/core-web-vitals/?utm_source=chatgpt.com
https://backlinko.com/google-ranking-factors?utm_source=chatgpt.com
https://www.debugbear.com/docs/core-web-vitals-ranking-factor?utm_source=chatgpt.com
https://huckabuy.com/25-important-core-web-vitals-statistics/?utm_source=chatgpt.com
https://vercel.com/blog/how-core-web-vitals-affect-seo?utm_source=chatgpt.com
Website of the Radio-Oncology Center Biel Seeeland Bernese Jura
