Performance Terms
Performance terms cover page speed and the technical signals that shape how fast a store feels. Each definition explains the metric and what influences it.
13 terms
Critical CSSCritical CSS is the minimum CSS needed to render above-the-fold content, inlined in HTML to eliminate render-blocking requests.PerformanceCumulative Layout ShiftA Core Web Vitals metric measuring how much visible content shifts unexpectedly during page load, causing a poor user experiencePerformanceINP (Interaction to Next Paint)INP measures the time from when a user interacts with a page to when the browser displays the visual response to that interaction.PerformanceLazy LoadingLazy loading defers loading of images and other resources until they are needed, reducing initial page load time and bandwidth usage.PerformanceLCP (Largest Contentful Paint)LCP measures the time it takes for the largest visible content element to render on screen, indicating perceived page load speed.PerformanceMinificationMinification removes unnecessary characters from code files without changing functionality, reducing file size and load times.PerformancePrefetchPrefetch is a resource hint that tells browsers to download resources the user will likely need for future page navigations.PerformancePreloadPreload is a browser resource hint that tells the browser to download a critical file early, before it would normally find it, so the page renders faster.PerformanceRender-Blocking ResourcesRender-blocking resources are CSS and JavaScript files that prevent the browser from displaying page content until they finish loading.PerformanceTBT (Total Blocking Time)TBT measures the total time the main thread was blocked by long tasks, preventing the page from responding to user input.PerformanceThird-Party ScriptsThird-party scripts are external JavaScript files loaded from other domains, such as analytics, ads, chat widgets, and social media buttons.PerformanceTTFB (Time to First Byte)TTFB measures the time between requesting a page and receiving the first byte of the response from the server.PerformanceWebPWebP is a modern image format developed by Google that provides superior compression compared to JPEG and PNG while maintaining visual quality.Performance
