Performance

Website speed and conversion — the measurable connection

Speed is not just a technical question — it is a business question. A slow website costs you conversions and customers.

Amazon found that 100 milliseconds of added load time reduced sales by 1%. Google data shows 53% of mobile users abandon a page that takes more than 3 seconds to load. Walmart found that every 1-second speed improvement increased conversions by 2%.

These are not hypotheses — these are measured results from analysis of the world's largest websites.

Why speed affects conversion

First impression forms quickly. A user decides within 50 milliseconds whether a page feels trustworthy. A slow-loading page gives the wrong signal before content even appears on screen.

Mobile is the dominant channel. Over 60% of web traffic comes from mobile devices, where connection speed is less stable and processors are weaker. A fast site on desktop can be unusable on mobile.

Google factors in speed. Core Web Vitals are a direct ranking signal. A slow site loses organic search positions to faster competitors.

Core Web Vitals — what to measure

Google measures three primary indicators:

LCP (Largest Contentful Paint) — when the largest content element loads. Good result: under 2.5 seconds.

CLS (Cumulative Layout Shift) — how much the page "jumps" during loading. Good result: under 0.1.

INP (Interaction to Next Paint) — how quickly the page responds to a user click. Good result: under 200ms.

Google Search Console shows these metrics using real user data.

Typical Drupal speed problems

Render-blocking resources — CSS and JS files block page rendering. Solution: aggregation and asynchronous loading.

Unoptimised images — the largest image files are often the LCP bottleneck. Solution: WebP format, lazy loading, appropriate image styles.

Missing cache — every visit generates the page from scratch. Solution: Drupal's Internal Page Cache, Redis, Varnish.

Third-party scripts — analytics, chat, ads. Each added script increases load time. Load these asynchronously or with lazy loading.

How to measure

  1. Google PageSpeed Insights — free, gives an immediate overview and recommendations
  2. WebPageTest — more detailed analysis, waterfall chart
  3. Google Search Console → Core Web Vitals — real user data, not lab conditions
  4. Lighthouse — in Chrome DevTools, detailed audit with priorities

Where to start

  1. Measure the current state — PageSpeed Insights and Search Console
  2. Identify the biggest bottlenecks (usually images and caching)
  3. Fix the highest-impact issues first
  4. Measure again

A speed audit is part of our Drupal audit and testing service — we deliver specific recommendations in priority order.

Kaido Toomingas Kaido Toomingas WebPro Company OÜ

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