

OK, but consider improvement = SI between 13 milliseconds.Good - nothing to do here = SI of 1311 milliseconds or less.GTmetrix displays the calculated Speed Index in seconds, with a lower time representing a faster loading webpage. Speed Index accounts for 10% of the total Performance Score.Įffectively, a lower SI indicates that above-the-fold content loaded much earlier, giving your visitors the perception of a faster loading page. Speed Index' effect on your Performance Score Use efficient CSS selectors (deprecated).Specify a viewport for mobile browsers (deprecated).Specify a Vary: Accept-Encoding header (deprecated).Serve static content from a cookieless domain (deprecated).Remove query strings from static resources (deprecated).Parallelize downloads across hostnames (deprecated).Optimize the order of styles and scripts (deprecated).Make landing page redirects cacheable (deprecated).Improve server response time (deprecated).Defer loading of JavaScript (deprecated).Combine external JavaScript (deprecated).

Avoid Flash on mobile webpages (deprecated).Avoid CSS Avoid CSS expressions (deprecated).Use passive listeners to improve scrolling performance.Use explicit width and height on image elements.Serve static assets with an efficient cache policy.Replace large JavaScript libraries with smaller alternatives (deprecated).Remove duplicate modules in JavaScript bundles.Lazy load third-party resources with facades.Keep request counts low and transfer sizes small.Ensure text remains visible during webfont load.Don't lazy load Largest Contentful Paint image.Avoid serving legacy JavaScript to modern browsers.
