create a macos code example of an extremely large list with high performance

To create an extremely large list with high performance in macOS using Swift, you can leverage various techniques discussed in the WWDC sessions. Here is an example that demonstrates how to create a high-performance list using Swift:

import SwiftUI

struct ContentView: View {
    let items = Array(0..<1000000) // 1 million items

    var body: some View {
        List(items, id: \.self) { item in
            Text("Item \(item)")
        }
        .onAppear {
            // Perform any additional setup or optimizations here
        }
    }
}

@main
struct MyApp: App {
    var body: some Scene {
        WindowGroup {
            ContentView()
        }
    }
}

Key Points for High Performance

1. Efficient Data Structures: Use efficient data structures to store your list items. In this example, an array is used, but for more complex data, consider using more appropriate structures.

2. Lazy Loading: SwiftUI's List is inherently optimized for large data sets by lazily loading items as they come into view.

3. Avoiding Unnecessary Copies: Minimize the use of reference types and unnecessary copying of data. Swift's value types (like structs) are generally more performant for large data sets.

4. Profiling and Optimization: Regularly profile your application to identify performance bottlenecks. Use tools like Instruments' flame graph to spot issues at a glance. For example, you can use the new flame graph feature in Xcode 16 to identify and optimize slow parts of your code. What’s new in Xcode 16 (19:44).

5. Memory Management: Be mindful of memory allocation and deallocation. Use techniques like autorelease pools to manage temporary memory growth effectively. For more details, you can refer to the session on managing autorelease pool growth in Swift. Analyze heap memory (10:34).

6. Swift Optimizations: Take advantage of Swift's powerful optimizer and ensure whole module optimization is enabled. This can significantly reduce overhead by allowing more inlining and other optimizations. Explore Swift performance (03:21).

By following these guidelines and leveraging the tools and techniques discussed in the WWDC sessions, you can create a high-performance list in macOS using Swift.