Page speed is part of the experience.
When the page is slow, customers leave before they even get to see your brand.
Load speed and smoothness of interactions are part of the brand experience, not just a side issue for the technical team. A slow page pushes customers away before they can read the first line, while a layout that jumps or lags when clicked undermines trust in professionalism. Google measures these aspects through the Core Web Vitals metrics and uses them as search ranking signals, so poor performance loses both customers and ranking.
- a sales website where every second drives customers away
- Pages with ads, images, and banners loading late need layout stability (CLS)
- performance checks on common devices and networks of real customers
- only measure speed on a powerful machine with a fast network and conclude that the page is fast
- run based on tool scores while neglecting real experiences on common phones
Page load speed and interface smoothness are not just technical team issues. They are part of the brand experience that customers perceive directly, often before they read a single line of content. A slow page not only drives customers away but also raises doubts about the seriousness of the business behind that page.
Three metrics to measure accurately the experience
Google has developed the Core Web Vitals metrics to measure three specific aspects of page loading experience, rather than just measuring general speed:
- LCP (Largest Contentful Paint): How long customers wait to see a significant part of the page, such as the hero image or main title. A good threshold is 2.5 seconds or less.
- INP (Interaction to Next Paint, interaction response time): After the customer clicks a button or types, how long does the interface take to respond? A good threshold is 200 milliseconds or less. Starting March 2024, INP will replace the old FID metric as it measures all interactions on the page, not just the first.
- CLS (Cumulative Layout Shift, cumulative layout shift): Does the content jump around while loading, causing customers to click incorrectly or lose their reading position? A good threshold is 0.1 or lower.
All three metrics are measured at the 75th percentile of load times, separated between mobile and desktop. This means that even if most customers find the page acceptable, if 1 in 4 loads is still slow or lagging, that number will still appear in the data.
The reason to measure on real phones.
A very common mistake is only testing speed on a desktop connected to a strong Wi-Fi network. That result does not reflect the experience of most customers in Vietnam, especially when they use mid-range phones with fluctuating 4G networks.
The Core Web Vitals threshold should be assessed based on real user data (field data), not just in the laboratory environment (lab data) of the tools. The devices and networks of real customers are often significantly weaker than those of web developers. High tool scores can still result in slow real experiences for customers if conditions are not measured accurately.
Common mistakes that slow down the page
- Images should not be compressed or kept at excessively large original sizes, causing LCP to slow down due to heavy files needing to load before displaying.
- Stuffing in many tracking codes and third-party utilities, such as chatbots, advertising pixels, and social media widgets. Each addition prolongs response times and worsens INP.
- Do not predefine sizes for images and embedded video frames. When the page loads, these elements have no size, causing layout shifts and increased CLS.
- Following the score of a tool without checking the real experience on common phones.
The viewpoint of Sinh Vũ
In the project handover, Sinh Vũ prioritizes basic SEO optimization and Core Web Vitals as part of the deliverables, linked to selecting the appropriate platform right from the technology stage. This is not an additional step at the end of the project but a technical criterion from the start.
Sinh Vũ does not commit to a specific score or a certain search ranking, as rankings depend on content and competition outside the design scope. What Sinh Vũ aims for is a technical foundation for fast loading, stable layout, and smooth responsive interfaces on real customer devices. That is the part Sinh Vũ can control and be responsible for.
Speed is not just a technical metric. Every additional second of waiting is a moment when customers begin to doubt.
Practical experience, Sinh Vũ Studio
Decision checklist
Topic: How speed and performance affect the experience. Sinh Vũ Handbook, sinhvu.com
Select each item you find appropriate, then print or save as PDF to take with you.
If you have marked most of the signs above, this is the time to discuss in more detail. Sinh Vũ can help you review and propose a direction.
References
Web Vitals, web.dev (Google). How the Core Web Vitals metrics thresholds were defined, web.dev. Understanding Core Web Vitals and Google Search results, Google for Developers.
Frequently asked questions
What are Core Web Vitals and why should you care?
Core Web Vitals are a set of three metrics used by Google to measure page loading experience: LCP measures the time to display the main content, INP measures the delay when users interact, and CLS measures layout stability. Starting March 2024, Google will use these metrics as search ranking signals, so pages that meet good thresholds will have an advantage over slower pages with the same content. More importantly, these metrics reflect the real experience of customers, not abstract technical numbers.
A high PageSpeed score means the page is fast for customers, right?
Not certain. PageSpeed Insights measures under laboratory conditions with simulated connections and devices, unlike common phones and actual 4G networks of users. Core Web Vitals should be measured on real user data, separating mobile and desktop. Many pages score high on the tool but are still slow for users on mid-range devices because they are only measured on powerful machines.