public sealed class DelCmd : ICommand
{
    private readonly Action<object?>? execute;
    private readonly Predicate<object?>? canExecute;
    public DelCmd(Action<object?>? executeValue, Predicate<object?>? canExecuteValue = null)
    {
        execute = executeValue;
        canExecute = canExecuteValue;
    }

    public event EventHandler? CanExecuteChanged;

    public bool CanExecute(object? parameter)
    {
        return canExecute?.Invoke(parameter) ?? true;
    }

    public void Execute(object? parameter)
    {
        execute?.Invoke(parameter);
    }

    public void RaiseCanExecuteChanged()
    {
        var handler = CanExecuteChanged;
        handler?.Invoke(this, EventArgs.Empty);
    }
}

public sealed class DelCmd<T> : ICommand
{
    private readonly Action<T?>? execute;
    private readonly Predicate<T?>? canExecute;
    public DelCmd(Action<T?>? executeValue, Predicate<T?>? canExecuteValue = null)
    {
        execute = executeValue ?? throw new ArgumentNullException(nameof(executeValue));
        canExecute = canExecuteValue;
    }

    public event EventHandler? CanExecuteChanged;

    public bool CanExecute(object? parameter)
    {
        if (canExecute is null)
        {
            return true;
        }

        T? para = default;
        if (parameter is T tPara)
        {
            para = tPara;
        }
        return canExecute(para);
    }

    public void Execute(object? parameter)
    {
        T? para = default;
        if (parameter is T tPara)
        {
            para = tPara;
        }
        execute?.Invoke(para);
    }

    public void RaiseCanExecuteChanged()
    {
        var handler = CanExecuteChanged;
        handler?.Invoke(this, EventArgs.Empty);
    }
}

<Window x:Class="WpfApp38.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:WpfApp38"
        mc:Ignorable="d"
        Title="{Binding MainTitle}" WindowState="Maximized">
    <Window.DataContext>
        <local:MainVM/>
    </Window.DataContext>
    <Grid>
        <DataGrid ItemsSource="{Binding BooksCollection}"
                  VirtualizingPanel.IsVirtualizing="True"
                  VirtualizingPanel.VirtualizationMode="Recycling"
                  VirtualizingPanel.CacheLength="5,5"
                  VirtualizingPanel.CacheLengthUnit="Item"
                  UseLayoutRounding="True"
                  SnapsToDevicePixels="True"
                  AutoGenerateColumns="True"
                  CanUserAddRows="False"
                  EnableRowVirtualization="True"
                  EnableColumnVirtualization="True"
                  ScrollViewer.IsDeferredScrollingEnabled="True"
                  ScrollViewer.CanContentScroll="True">
            <DataGrid.Resources>
                <Style TargetType="DataGridRow">
                    <Setter Property="FontSize" Value="30"/>
                    <Style.Triggers>
                        <Trigger Property="IsMouseOver" Value="True">
                            <Setter Property="FontSize" Value="40"/>
                            <Setter Property="Foreground" Value="Red"/>
                        </Trigger>
                    </Style.Triggers>
                </Style>
            </DataGrid.Resources>
            <DataGrid.ContextMenu>
                <ContextMenu>
                    <MenuItem Header="Load Data"
                              FontSize="30"
                              Command="{Binding LoadCmd}"/>
                </ContextMenu>
            </DataGrid.ContextMenu>
        </DataGrid>
    </Grid>
</Window>


using System.Collections.ObjectModel;
using System.ComponentModel;
using System.Diagnostics.Eventing.Reader;
using System.Drawing.Imaging.Effects;
using System.Runtime.CompilerServices;
using System.Security.RightsManagement;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;
using Debug = System.Diagnostics.Debug;

namespace WpfApp38
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
        }
    }

    public class MainVM : INotifyPropertyChanged
    {
        public DelCmd LoadCmd { get; set; }

        private static long id = 0;
        public MainVM()
        {
            LoadCmd = new DelCmd(LoadCmdExecuted);
            LoadCmd.RaiseCanExecuteChanged();
            _= LoadDataLoopsAsync();
        }

        private void LoadCmdExecuted(object? obj)
        {
            _ = LoadDataAsync();
        }

        private async Task LoadDataLoopsAsync()
        {
            while (true)
            {
                try
                {
                    await LoadDataAsync();
                }
                catch (Exception ex)
                {
                    Debug.WriteLine($"{DateTime.Now},{ex.Message}");
                }                
                await Task.Delay(20000);
            }
        }

        private async Task LoadDataAsync()
        {
            List<Book> bksList = new List<Book>();
            for (int i = 0; i < 2000000; i++)
            {
                var a = GetIncrementId();
                bksList.Add(new Book()
                {
                    Id = a,
                    Name = $"Name_{a}",
                    ISBN = $"ISBN_{a}_{Guid.NewGuid():N}",
                    Comment = $"Comment_{a}",
                    Content = $"Content_{a}",
                    Abstract = $"Abstract_{a}",
                    Author = $"Author_{a}",
                    Summary = $"Summary_{a}",
                    Title = $"Title_{a}",
                    Topic = $"Topic_{a}"
                });
            }

            await Application.Current.Dispatcher.InvokeAsync(() =>
            {
                BooksCollection = new ObservableCollection<Book>(bksList);
                bksList.Clear();
                MainTitle = $"{DateTime.Now},loaded {BooksCollection.Count} items,first Id:{BooksCollection.FirstOrDefault()?.Id},last Id:{BooksCollection.LastOrDefault()?.Id}";
            }, System.Windows.Threading.DispatcherPriority.Background);
        }

        private static long GetIncrementId()
        {
            return Interlocked.Increment(ref id);
        }

        private string mainTitle;
        public string MainTitle
        {
            get
            {
                return mainTitle;
            }
            set
            {
                if (value != mainTitle)
                {
                    mainTitle = value;
                    OnPropertyChanged();
                }
            }
        }

        private ObservableCollection<Book> booksCollection;
        public ObservableCollection<Book> BooksCollection
        {
            get
            {
                return booksCollection;
            }
            set
            {
                if (value != booksCollection)
                {
                    booksCollection = value;
                    OnPropertyChanged();
                }
            }
        }

        public event PropertyChangedEventHandler? PropertyChanged;
        private void OnPropertyChanged([CallerMemberName] string propName = "")
        {
            var handler = PropertyChanged;
            handler?.Invoke(this, new PropertyChangedEventArgs(propName));
        }
    }

    public sealed class DelCmd : ICommand
    {
        private readonly Action<object?>? execute;
        private readonly Predicate<object?>? canExecute;
        public DelCmd(Action<object?>? executeValue, Predicate<object?>? canExecuteValue = null)
        {
            execute = executeValue;
            canExecute = canExecuteValue;
        }

        public event EventHandler? CanExecuteChanged;

        public bool CanExecute(object? parameter)
        {
            return canExecute?.Invoke(parameter) ?? true;
        }

        public void Execute(object? parameter)
        {
            execute?.Invoke(parameter);
        }

        public void RaiseCanExecuteChanged()
        {
            var handler = CanExecuteChanged;
            handler?.Invoke(this, EventArgs.Empty);
        }
    }

    public sealed class DelCmd<T> : ICommand
    {
        private readonly Action<T?>? execute;
        private readonly Predicate<T?>? canExecute;
        public DelCmd(Action<T?>? executeValue, Predicate<T?>? canExecuteValue = null)
        {
            execute = executeValue ?? throw new ArgumentNullException(nameof(executeValue));
            canExecute = canExecuteValue;
        }

        public event EventHandler? CanExecuteChanged;

        public bool CanExecute(object? parameter)
        {
            if (canExecute is null)
            {
                return true;
            }

            T? para = default;
            if (parameter is T tPara)
            {
                para = tPara;
            }
            return canExecute(para);
        }

        public void Execute(object? parameter)
        {
            T? para = default;
            if (parameter is T tPara)
            {
                para = tPara;
            }
            execute?.Invoke(para);
        }

        public void RaiseCanExecuteChanged()
        {
            var handler = CanExecuteChanged;
            handler?.Invoke(this, EventArgs.Empty);
        }
    }

    public class Book
    {
        public long Id { get; set; }
        public string Name { get; set; }
        public string ISBN { get; set; }
        public string Comment { get; set; }
        public string Content { get; set; }
        public string Author { get; set; }
        public string Abstract { get; set; }
        public string Summary { get; set; }
        public string Title { get; set; }
        public string Topic { get; set; }
    }
}