In 2021, Google confirmed what many SEOs had suspected for years: page experience signals — including load speed, visual stability, and responsiveness — are official ranking factors. The Core Web Vitals update formalised this, and Google has continued to increase the weight of performance signals in its ranking algorithm since.
But the SEO impact of page speed is only half the story. A slow landing page also converts at a fraction of the rate of a fast one. Google research shows that as page load time increases from 1 second to 3 seconds, the probability of a visitor bouncing increases by 32%. At 5 seconds, that figure is 90%. You can rank a slow page — but you cannot easily convert from it.
This is why performance is built into every project we produce at Redmark. It is not an optional optimisation pass at the end — it is a core requirement from the first line of code.
Core Web Vitals: What Google Actually Measures
Google's Core Web Vitals are three specific, user-centred performance metrics that directly affect your search rankings:
- Largest Contentful Paint (LCP) — measures how quickly the largest visible element on the page loads. Google's target is under 2.5 seconds. This is most commonly affected by hero images, background images, and render-blocking scripts
- Cumulative Layout Shift (CLS) — measures visual stability, specifically how much page elements shift position as the page loads. Unexpected layout shifts are jarring and signal a poorly built page. Target: below 0.1
- Interaction to Next Paint (INP) — replaced First Input Delay in 2024 and measures how quickly the page responds to user interactions. Heavy JavaScript execution is the most common cause of poor INP scores
These are not abstract technical scores. They correspond directly to how the page feels to a real user on a real device. A page that scores well on all three Core Web Vitals will feel fast, stable, and responsive — and will receive a ranking advantage over slower pages targeting the same keywords.
How Speed Affects Organic Search Rankings
Page speed affects SEO in two distinct ways. The direct effect is the ranking signal itself — Google's algorithm now includes Core Web Vitals as a tiebreaker between pages of similar content quality and relevance. For competitive keywords where multiple well-optimised pages compete, performance can be the deciding factor in ranking position.
The indirect effect is through engagement signals. If your page loads slowly and visitors bounce, Google interprets that as a signal that your page is not satisfying the search intent — even if your content is excellent. High bounce rates and low dwell time send negative signals that can suppress rankings over time.
Conversely, a fast, engaging page that users actually read and interact with accumulates positive engagement signals that reinforce and improve rankings. The relationship between performance and SEO is self-reinforcing in both directions.
Performance's Impact on Paid Advertising
If you are running Google Ads, your landing page speed directly affects your Quality Score. Google calculates Quality Score from three factors: expected clickthrough rate, ad relevance, and landing page experience. Page speed is explicitly a component of landing page experience.
A poor Quality Score means you pay more per click for the same ad position, or receive worse positions at the same bid. A slow landing page receiving 1,000 paid clicks per month could be costing you 20-30% more per click than a fast equivalent page targeting the same audience.
This compounds the conversion loss from slow load times — you are paying more per visitor to get fewer of them to convert. We explore this in more detail in our guide to how landing pages improve paid advertising performance.
The Most Common Causes of Slow Landing Pages
Most slow landing pages share the same root causes. Understanding them is the first step to addressing them:
- Unoptimised images — the most common culprit. A hero image saved at full resolution can be 3-5MB; the same image correctly exported as WebP at the right dimensions should be under 200KB
- Render-blocking scripts — JavaScript loaded in the `<head>` that must execute before the page can render. Third-party scripts (chat widgets, analytics, tag managers) are frequent offenders
- Template overhead — page builders and themes often ship with hundreds of kilobytes of CSS and JavaScript for features you are not using. This is one of the most significant performance advantages of custom-built pages over templates
- No caching headers — returning visitors should be served cached assets, not re-downloading everything on each visit
- Poor hosting — shared hosting with high server response times (TTFB above 200ms) creates a performance ceiling that no amount of front-end optimisation can fully overcome
- Excessive font weights — loading eight font weights when three are used adds unnecessary payload. Each unused weight is a network request that delays render
Performance and Conversion Rate: The Combined Effect
The compounding effect of speed on both SEO and conversion rate creates a significant business case for performance investment. A page that loads in 1 second compared to 4 seconds might:
- Rank 2-3 positions higher for competitive keywords, generating more organic traffic
- Reduce bounce rate by 40-60%, keeping more visitors on the page long enough to convert
- Improve Quality Score in Google Ads, reducing cost-per-click by 15-25%
- Improve overall conversion rate by 15-30% through lower friction and better perceived quality
Each of these effects operates independently, but they compound together. Better rankings bring more traffic. Lower bounce rates mean more of that traffic engages. Better conversion rates mean more of those engaged visitors become leads. Better Quality Scores mean you can scale paid traffic more efficiently.
A high converting landing page and a fast landing page are not two separate objectives — they are the same objective, approached from different angles.
How We Build for Performance at Redmark
Performance is a design and architecture decision, not a final-stage optimisation. At Redmark, every project is built with the following performance principles applied from the start:
- Custom HTML/CSS with no unnecessary dependencies — every file that loads has a purpose on that specific page
- Images exported as WebP at precise dimensions, with explicit width and height attributes to prevent layout shift
- Non-critical JavaScript loaded asynchronously and deferred where possible
- Google Fonts loaded with `rel="preconnect"` and `display=swap` to prevent render blocking
- No page builders, no themes, no bloat — clean, minimal code that scores well on Core Web Vitals by design
If you would like to discuss how a performance-focused rebuild could improve your search rankings and conversion rates, start a project with us. We work with businesses across the UK and internationally to build landing pages that are fast, optimised, and designed to generate results.