Video: React Concurrency, Explained

The useTransition hook in React helps manage state updates more smoothly by marking certain updates as non-urgent. This allows the UI to remain responsive as these updates are processed asynchronously, preventing the interface from freezing during heavy computations.

React handles non-urgent updates by allowing them to be interrupted. This is facilitated by the StartTransition API, where updates wrapped in startTransition are treated as non-urgent and can be paused or stopped to allow more urgent updates to process first.

To address performance issues in React applications, developers can use techniques such as memoization, component optimization, list virtualization, debouncing, and throttling. Additionally, React 18 introduces the concept of non-urgent updates, which can also help manage performance more effectively.

While concurrent rendering provides many benefits, it has some drawbacks such as increased complexity in the React architecture, potentially longer times for non-urgent updates, and increased CPU usage due to the need to check and yield back control to the browser frequently.

UseTransition is particularly useful in scenarios where updates can be perceived as non-urgent, such as filtering a list of items, fetching data in the background, or handling input in complex forms. It helps keep the app responsive by relegating these updates to the background when necessary.

Using startTransition in React 18 helps improve UI responsiveness by marking certain state updates as non-urgent. This prevents the UI from freezing by allowing the browser to interrupt these updates if necessary, leading to a smoother user experience.

Concurrent rendering, previously known as Time Slicing, is a feature in React that allows for non-urgent updates to be processed in a way that doesn't block the main thread, enabling smoother and more responsive UI experiences. It includes hooks like useTransition and useDefaultValue, and improvements around suspense and hydration.