{"id":1170,"date":"2025-05-21T11:01:19","date_gmt":"2025-05-21T11:01:19","guid":{"rendered":"https:\/\/www.cmarix.com\/qanda\/?p=1170"},"modified":"2026-02-05T12:06:16","modified_gmt":"2026-02-05T12:06:16","slug":"react-18-concurrent-rendering-explained","status":"publish","type":"post","link":"https:\/\/www.cmarix.com\/qanda\/react-18-concurrent-rendering-explained\/","title":{"rendered":"What is Concurrent Rendering in React 18 and How Does It Improve Performance?"},"content":{"rendered":"\n<p>Concurrent Rendering is a foundational change in React 18&#8217;s rendering mechanism. Instead of rendering being a single, synchronous, uninterruptible task, React can now prepare multiple versions of the UI simultaneously. It allows React to interrupt a long-running render (e.g., rendering a complex data grid) to handle a higher-priority update (like user input), pause it, resume it later, or even abandon the in-progress work if it becomes stale (e.g., data changes before the render completes). This makes apps more responsive by prioritizing user interactions over background rendering tasks.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">How it Improves Performance &amp; Responsiveness:<\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Non-blocking UI<\/strong>: Prevents the UI from freezing during expensive renders.<\/li>\n\n\n\n<li><strong>Better Resource Utilization<\/strong>: Works on lower-priority tasks during idle time.<\/li>\n\n\n\n<li><strong>Enables New Features<\/strong>: Powers useTransition, useDeferredValue, Suspense for data fetching.<\/li>\n<\/ul>\n\n\n\n<p>Example \u2013 using useTransition:<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>const &#91;isPending, startTransition] = useTransition();\n\/\/ High priority update (e.g., typing in an input)\nsetInputValue(newValue);\n\/\/ Low priority update (can be interrupted)\nstartTransition(() => {\n  setSearchResults(newValue); \/\/ Heavy operation\n});\n\/\/ Show loading state: {isPending &amp;&amp; &lt;Spinner \/>}<\/code><\/pre>\n","protected":false},"excerpt":{"rendered":"<p>Concurrent Rendering is a foundational change in React 18&#8217;s rendering mechanism. Instead of rendering being a single, synchronous, uninterruptible task, React can now prepare multiple versions of the UI simultaneously. It allows React to interrupt a long-running render (e.g., rendering a complex data grid) to handle a higher-priority update (like user input), pause it, resume [&hellip;]<\/p>\n","protected":false},"author":2,"featured_media":1173,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[6,3],"tags":[],"class_list":["post-1170","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-react","category-web"],"acf":[],"_links":{"self":[{"href":"https:\/\/www.cmarix.com\/qanda\/wp-json\/wp\/v2\/posts\/1170","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.cmarix.com\/qanda\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.cmarix.com\/qanda\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.cmarix.com\/qanda\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.cmarix.com\/qanda\/wp-json\/wp\/v2\/comments?post=1170"}],"version-history":[{"count":5,"href":"https:\/\/www.cmarix.com\/qanda\/wp-json\/wp\/v2\/posts\/1170\/revisions"}],"predecessor-version":[{"id":1177,"href":"https:\/\/www.cmarix.com\/qanda\/wp-json\/wp\/v2\/posts\/1170\/revisions\/1177"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.cmarix.com\/qanda\/wp-json\/wp\/v2\/media\/1173"}],"wp:attachment":[{"href":"https:\/\/www.cmarix.com\/qanda\/wp-json\/wp\/v2\/media?parent=1170"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.cmarix.com\/qanda\/wp-json\/wp\/v2\/categories?post=1170"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.cmarix.com\/qanda\/wp-json\/wp\/v2\/tags?post=1170"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}