React 16 introduces a performance improvement that allows developers to prevent unnecessary component re-renders by utilizing the .setState method to check if the new state value is identical to the existing one and, if so, returning null to avoid a state update. This technique is demonstrated through a mocktail selection app, where the App component handles mocktail state updates via a method called updateMocktail. The app initially updates the mocktail image each time a selection button is clicked, even if the same mocktail is chosen repeatedly, causing redundant re-renders. By modifying the updateMocktail method to compare the new and existing mocktail values and only trigger a state update if they differ, React 16 avoids unnecessary re-renders, thus enhancing the app's performance and user experience. The approach not only optimizes state management but also aligns with the goal of delivering a seamless and responsive application interface that meets user expectations.