Users do not see metrics. They feel delays. Google tries to measure that feeling. This post connects milliseconds to money and rankings, making one thing undeniable: Performance is user experience.

Performance is felt before it’s measured

Core Web Vitals are Google’s attempt to quantify human frustration. But before we talk about scores, we must talk about feelings.

When a user taps a button and nothing happens, they don’t think “The Interaction to Next Paint is high.” They think “This is broken.” When a layout shifts while they are reading, they don’t think “The Cumulative Layout Shift is 0.2.” They think “This is annoying.”

Performance is the foundation of user experience. If your site is slow, it doesn’t matter how beautiful your design is or how relevant your content is. The user’s first impression is already tarnished.

The psychology of speed

There is a direct link between site speed and human psychology. We are wired to expect immediate feedback. In the physical world, when you touch something, you feel it instantly. When the digital world breaks this expectation, it breaks our flow.

• Delays break flow: Every pause forces the brain to re-contextualize.
• Jank kills trust: A jerky interface feels cheap and unreliable.
• Shifting UI feels broken: It suggests the system is not in control.

The key takeaway is simple: Users blame your product, not their network. They won’t say “My 4G is slow.” They will say “This website is slow.”

From perception to metrics

Google’s Core Web Vitals are an attempt to map these human perceptions to engineering metrics. They answer three critical questions users subconsciously ask:

Human Perception	Metric	Technical Name
”It loaded”	LCP	Largest Contentful Paint
”It responds”	INP	Interaction to Next Paint
”It is stable”	CLS	Cumulative Layout Shift

These three metrics cover the majority of user experience pain points. LCP measures how fast the main content is visible. INP measures how quickly the page responds to a tap or key press. CLS measures visual stability. If you optimize these, you aren’t just improving numbers; you are removing specific frustrations.

Why milliseconds matter

User experience does not degrade linearly. A 100ms delay is barely noticeable. A 300ms delay is perceptible. A 1-second delay interrupts a user’s train of thought.

Small delays compound. If every interaction has a slight lag, the entire experience feels “heavy” or “sluggish.” Crucially, the worst moments dominate memory. A user might have ten fast interactions, but if the checkout button freezes for three seconds, that is what they will remember. This is why metrics like INP focus on the outliers—the slowest interactions—because those define the experience.

Performance and engagement

The link between performance and business metrics is causal, not just correlational.

• Faster sites reduce bounce: If content appears instantly, users stay. If they stare at a white screen, they leave.
• Stable layouts increase trust: If a page jumps around, users are scared to click. Stability signals quality.
• Responsive UIs increase task completion: When the interface feels responsive, users are more likely to complete complex tasks like filling out forms or checking out.

It’s not about “fake numbers” or gaming the system. It’s about mechanics. A layout shift causes a misclick on an ad, annoying the user. A slow interaction makes a user think their payment failed, causing them to abandon the cart.

Performance as a Google ranking signal

Let’s be precise about SEO. Core Web Vitals are part of the Page Experience signal.

They are not the strongest ranking factor. Content relevance is still king. If you have the best answer to a user’s question, you will likely rank well even with mediocre performance.

However, they are tie-breakers. If two pages have similar content quality and relevance, the faster, more stable experience will rank higher. More importantly, bad performance can cap the potential of good content. If your page is so slow that users bounce before Google can even measure their engagement, your rankings will suffer.

Field data vs lab data (SEO reality)

There is a massive misunderstanding in many engineering teams about which data matters.

• Lab data (Lighthouse scores on your MacBook): Irrelevant to ranking.
• Field data (CrUX - Chrome UX Report): This is what Google uses.

Google ranks your site based on what real users experience, not what your simulation says. This data comes from the Chrome UX Report (CrUX), which aggregates data from real users on real devices across real networks.

This is why you can have a “100” Lighthouse score and still fail Core Web Vitals. Your developer laptop on fast WiFi is not representative of a user on a mid-range Android phone on a 3G network. Real frustration happens in the field.

Why improving CWV helps SEO indirectly

The direct ranking boost from CWV is real, but the indirect benefits are often larger.

Better Core Web Vitals lead to:

1. Lower bounce rates: Users stick around.
2. Longer sessions: Users consume more content.
3. Higher engagement signals: Users interact more.

Google’s ranking algorithms rely heavily on user signals. If users dwell on your page and interact with it, Google sees that as a signal of quality. Performance amplifies content quality. A fast site gives your content the best possible chance to shine.

The cost of ignoring performance

Ignoring performance creates silent debt.

• Good content underperforms: You write great posts, but no one waits for them to load.
• Marketing spends more: You pay for clicks, but users bounce before the landing page renders.
• SEO plateaus: You optimize keywords, but user experience signals drag you down.

Performance debt compounds. It is much harder to fix a slow architecture than to build a fast one from the start.

How teams should think about performance

We need to shift the mindset. Performance is:

• Not an optimization phase at the end of a sprint.
• Not solely an SEO task for the marketing team.
• A product quality baseline.

Performance decisions are design decisions. Choosing a heavy font, a massive hero image, or a complex client-side framework are all tradeoffs that affect the user.

Conclusion

Every millisecond affects perception. Core Web Vitals are just a way to measure real human frustration. SEO rewards better experiences, not just cleaner code.

If there is one thing to take away, it is this: You do not optimize for Google. You optimize for users—and Google notices.

I hope this has been helpful and/or taught you something new!

@khriztianmoreno

Until next time.