Xcode 16 SwiftUI List Fast Scrolling Issue

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Hello,

I have also been experiencing the same issue when trying to implement a section index for a List in SwiftUI.

Please see below for a simple example from a test project (created with the default Xcode 16 build settings, no other changes) that reproduces the same issue outlined by the OP.

import SwiftUI

struct ContentView: View {
    
    let sections: [String] = ["#", "A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z"]
    
    var body: some View {
        ScrollViewReader { proxy in
            ZStack {
                List {
                    ForEach(sections, id: \.self) { section in
                        Section(section) {
                            ForEach(0...25, id: \.self) { _ in
                                Text("Hello, \(section)!")
                            }
                        }
                    }
                }
                .listStyle(.plain)
                .padding(.trailing)
                HStack {
                    Spacer()
                    SectionIndexTitles(proxy: proxy, titles: sections)
                }
            }
        }
        .scrollIndicators(.never)
    }
}

struct SectionIndexTitles: View {
    let proxy: ScrollViewProxy
    let titles: [String]
    @GestureState private var dragLocation: CGPoint = .zero
    
    var body: some View {
        VStack {
            ForEach(titles, id: \.self) { title in
                Text(title)
                    .font(.footnote)
                    .fontWeight(.semibold)
                    .background(dragObserver(title: title))
            }
        }
        .padding(.horizontal, 2.5)
        .gesture(DragGesture(minimumDistance: 0, coordinateSpace: .global).updating($dragLocation, body: { value, state, _ in
            state = value.location
        }))
    }
    
    func dragObserver(title: String) -> some View {
        GeometryReader { geometry in
            dragObserver(geometry: geometry, title: title)
        }
    }
    
    func dragObserver(geometry: GeometryProxy, title: String) -> some View {
        if geometry.frame(in: .global).contains(dragLocation) {
            DispatchQueue.main.async {
                proxy.scrollTo(title, anchor: .top)
            }
        }
        return Rectangle().fill(Color.clear)
    }
}

Thank you, Alex