Page Speed

Understanding Page Speed

Page speed is not a single number but a collection of metrics that capture different aspects of the loading experience. Largest Contentful Paint (LCP) measures when the main content of the page becomes visible, ideally under 2.5 seconds. Interaction to Next Paint (INP), which replaced First Input Delay in 2024, measures responsiveness to user interactions, ideally under 200 milliseconds. Cumulative Layout Shift (CLS) measures visual stability, ensuring elements do not jump around as the page loads, ideally under 0.1.

For e-commerce stores, the most common page speed killers are unoptimized images, excessive third-party scripts (apps, analytics, chat widgets, pop-ups), render-blocking CSS and JavaScript, and slow server response times. A typical Shopify store might have 15-25 third-party scripts loading on every page, each adding latency and competing for the browser's limited resources. Review widgets, in particular, can be significant contributors to page weight if they load large amounts of review content, customer photos, and interactive elements synchronously.

Google uses Core Web Vitals as a ranking signal, meaning slow pages are at a disadvantage in organic search results. Beyond SEO, the direct impact on conversion is well-documented: Amazon famously found that every 100ms of added latency cost them 1% in sales. For smaller stores, the impact is proportionally similar. A store loading in 2 seconds versus 5 seconds will see meaningfully different conversion rates, bounce rates, and average session durations.

Optimizing page speed requires a systematic approach. Start by auditing with tools like Google PageSpeed Insights, Lighthouse, and WebPageTest. Identify the biggest contributors to load time, often images and third-party scripts. Implement lazy loading for below-the-fold content, compress and properly size images, defer non-critical JavaScript, and critically evaluate whether each installed app provides enough value to justify its performance cost.