what are the adventages of the "idle prefetch" improvement coming to macos?

The "idle prefetch" improvement coming to macOS offers several advantages, particularly in enhancing performance and user experience. This technique, previously used in iOS, SwiftUI, and UIKit, takes advantage of idle time after rendering the current frame to pre-render the next frame. This approach helps reduce the likelihood of dropping frames during scrolling, resulting in smoother scrolling experiences.

With the introduction of idle prefetch to macOS, there is a significant boost in performance. For instance, lists and tables in SwiftUI can now handle very large amounts of data more efficiently. On macOS, a list of 100,000 items will load over six times faster, and incremental changes like inserting new items are up to 16 times faster. Larger lists will see even bigger performance gains. These improvements collectively represent a substantial step forward in SwiftUI scrolling performance on macOS.

For more details, you can refer to the Platforms State of the Union (43:43) session.