Explicit concurrent copying GC freed, Xamarin.Forms

Question

I want to create the data model asynchronously. I am using MVVM. My code looks like this.

class Page (code behind):

public partial class PageMusicPlayerView : TabbedPage
{
    public PageMusicPlayerView()
    {
        InitializeComponent();
        PageMusicPlayerViewModel viewModel = PageMusicPlayerViewModel.GetInstance();
        BindingContext = viewModel;
    }

    protected override async void OnAppearing()
    {
        await PageMusicPlayerViewModel.GetInstance().InitAsync();
    }

}

class PageMusicPlayerViewModel (view model):

public class PageMusicPlayerViewModel : NotifyProperty
{
    private static PageMusicPlayerViewModel instance = null;

    public static PageMusicPlayerViewModel GetInstance()
    {
        if (instance == null)
        {
            instance = new PageMusicPlayerViewModel();

        }
        return instance;
    }

    public MusicPlaylistModel MusicPlaylist { get; set; } = MusicPlaylistModel.GetInstance();

    public async Task InitAsync()
    {
        await MusicPlaylist.InitAsync();
    }

}

class MusicPlaylistModel (model):

public class MusicPlaylistModel : NotifyProperty
{
    private static MusicPlaylistModel instance = null;

    ObservableCollection<MusicItemModel> _listMusic;

    public ObservableCollection<MusicItemModel> ListMusic
    {
        get { return _listMusic; }
        set { SetProperty(ref _listMusic, value); }
    } 

    public static MusicPlaylistModel GetInstance()
    {
        if(instance == null)
        {
            instance = new MusicPlaylistModel();
        }
        return instance;
    }

    private MusicPlaylistModel()
    {
        ListMusic = new ObservableCollection<MusicItemModel>();
    }

    public async Task InitAsync()
    {
        int size = 8000;
        for(int i = 0;i<size;i++)
        {
            ListMusic.Add(new MusicItemModel { SoundName = "TEST" });
        }
    }
 
}

class MusicItemModel (model):

public class MusicItemModel : NotifyProperty
{
    long _id = -1;
    string _soundName = string.Empty;
    string _soundDuration = string.Empty;
    bool _cached = false;
    string _downloadingLabel = string.Empty;

    public long Id
    {
        get { return _id; }
        set { SetProperty(ref _id, value); }
    }
    public string SoundName
    {
        get { return _soundName; }
        set { SetProperty(ref _soundName, value); }
    }
    public string SoundDuration
    {
        get { return _soundDuration; }
        set { SetProperty(ref _soundDuration, value); }
    }
    public bool Cached
    {
        get { return _cached; }
        set { SetProperty(ref _cached, value); }
    }
    [NotMapped]
    public string DownloadingLabel
    {
        get { return _downloadingLabel; }
        set 
        {
            SetProperty(ref _downloadingLabel, value); 
        }
    }

}

Model ListMusic is bound to a view. I provide the MusicItemModel class as is, everything else is reduced to a minimal example. I am getting errors while running the application. Also, the debugger starts to freeze a lot:

Explicit concurrent copying GC freed 9420(1219KB) AllocSpace objects, 0(0B) LOS objects, 71% free, 2406KB/8550KB, paused 33us total 10.883ms
Explicit concurrent copying GC freed 717(39KB) AllocSpace objects, 0(0B) LOS objects, 72% free, 2382KB/8526KB, paused 24us total 8.730ms
Explicit concurrent copying GC freed 15(48KB) AllocSpace objects, 0(0B) LOS objects, 72% free, 2382KB/8526KB, paused 20us total 8.058ms
Explicit concurrent copying GC freed 3(16KB) AllocSpace objects, 0(0B) LOS objects, 72% free, 2382KB/8526KB, paused 24us total 8.521ms
Explicit concurrent copying GC freed 6(32KB) AllocSpace objects, 0(0B) LOS objects, 72% free, 2382KB/8526KB, paused 24us total 8.279ms
Explicit concurrent copying GC freed 3(16KB) AllocSpace objects, 0(0B) LOS objects, 72% free, 2382KB/8526KB, paused 22us total 8.190ms
Explicit concurrent copying GC freed 3(16KB) AllocSpace objects, 0(0B) LOS objects, 72% free, 2382KB/8526KB, paused 22us total 8.067ms
Explicit concurrent copying GC freed 32(48KB) AllocSpace objects, 0(0B) LOS objects, 72% free, 2382KB/8526KB, paused 22us total 7.973ms

Errors are only under debugging in Visual Studio. If I run a debug build without debugging everything works fine and fast. Why is this happening? Android 10, Huawei P30.

P.S.: If I reduce the size of the variable size to 1000 and below, then the problems go away. But the amount of my data in the real sample is 8276 elements.

Answer 1

The extreme lagginess with an ObservableCollection having 8000 elements, was due to Hot Reload.

UNCHECK Hot Reload in Tools/Options resolved the performance issue.