优化图标加载方式，将工作分配到独立线程，减少UI卡顿；优化文件夹加载方式，当文件很多时，会采用惰性加载策略。

ExplorerEx/App.xaml

@@ -22,6 +22,7 @@
                     <c:Int2VisibilityConverter x:Key="Int2VisibilityConverter"/>
                     <c:Int2VisibilityReConverter x:Key="Int2VisibilityReConverter"/>
                     <c:FileName2IconConverter x:Key="FileName2IconConverter"/>
+                    <c:FileDateTime2StringConverter x:Key="FileDateTime2StringConverter"/>
                     <c:FullPath2FileNameConverter x:Key="FullPath2FileNameConverter"/>
                     <c:Bytes2StringConverter x:Key="Bytes2StringConverter"/>
                     <u:LangConverter x:Key="LangConverter"/>

ExplorerEx/App.xaml.cs

@@ -16,13 +16,10 @@
 namespace ExplorerEx;
 
 public partial class App {
-	public static App Instance { get; private set; } = null!;
 	public static Arguments Args { get; private set; } = null!;
 	public static int ProcessorCount { get; private set; }
 
-	private App() {
-		Instance = this;
-	}
+	private App() { }
 
 	private static bool isRunning;
 	private static Mutex? mutex;
@@ -66,8 +63,9 @@ public partial class App {
 			IsBackground = true
 		}.Start();
 
+		ProcessorCount = Environment.ProcessorCount;
+
 		Encoding.RegisterProvider(CodePagesEncodingProvider.Instance);
-		Shell32Interop.Initialize();
 		IconHelper.InitializeDefaultIcons(Resources);
 		Settings.Current.LoadSettings();
 		ChangeTheme(((SolidColorBrush)SystemParameters.WindowGlassBrush).Color, false);

ExplorerEx/Command/FileItemCommand.cs

@@ -102,7 +102,7 @@ public class FileItemCommand : ICommand {
 				break;
 			}
 			case "Paste": {
-				if (Folder != null && Clipboard.GetDataObject() is DataObject data) {
+				if (Clipboard.GetDataObject() is DataObject data) {
 					if (data.GetData(DataFormats.FileDrop) is string[] filePaths) {
 						bool isCut;
 						if (data.GetData("IsCut") is bool i) {
@@ -136,9 +136,6 @@ public class FileItemCommand : ICommand {
 				break;
 			}
 			case "Delete":  // 删除一个或多个文件，按住shift就是强制删除
-				if (Folder == null) {
-					return;
-				}
 				if ((Keyboard.Modifiers & ModifierKeys.Shift) != ModifierKeys.Shift) {  // 没有按Shift
 					if (!MessageBoxHelper.AskWithDefault("Recycle", "#AreYouSureToRecycleTheseFiles".L())) {
 						return;
@@ -200,9 +197,7 @@ public class FileItemCommand : ICommand {
 				}
 				break;
 			case "Terminal":
-				if (Folder != null) {
-					Terminal.RunTerminal(Folder.FullPath);
-				}
+				Terminal.RunTerminal(Folder.FullPath);
 				break;
 			case "ShowMore": {
 				if (!ConfigHelper.LoadBoolean("ShowMore")) {

ExplorerEx/Converter/FileDateTime2StringConverter.cs

@@ -0,0 +1,19 @@
+using System;
+using System.Globalization;
+using System.Windows.Data;
+
+namespace ExplorerEx.Converter; 
+
+internal class FileDateTime2StringConverter : IValueConverter {
+	public object Convert(object value, Type targetType, object parameter, CultureInfo culture) {
+		var dt = (DateTime)value;
+		if (dt == DateTime.MaxValue) {
+			return string.Empty;
+		}
+		return dt.ToString(CultureInfo.CurrentUICulture);
+	}
+
+	public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture) {
+		throw new NotImplementedException();
+	}
+}

ExplorerEx/Model/FileItem/Bookmark.cs

@@ -42,7 +42,7 @@ public class BookmarkCategory : NotifyPropertyChangedBase {
 
 	public virtual ObservableCollection<BookmarkItem>? Children { get; set; }
 
-	public BookmarkCategory() { }
+	private BookmarkCategory() { }
 
 	public BookmarkCategory(string name) {
 		Name = name;
@@ -71,9 +71,9 @@ public class BookmarkItem : FileListViewItem, IFilterable {
 
 	public BookmarkCategory Category { get; set; } = null!;
 
-	public BookmarkItem() : base(null!, null!) { }
+	private BookmarkItem() : base(null!, null!, false) { }
 
-	public BookmarkItem(string fullPath, string name, BookmarkCategory category) : base(null!, null!) {
+	public BookmarkItem(string fullPath, string name, BookmarkCategory category) : base(null!, null!, false) {
 		FullPath = Path.GetFullPath(fullPath);
 		Name = name;
 		Category = category;

ExplorerEx/Model/FileItem/FileListViewItem.cs

@@ -13,15 +13,23 @@
 using ExplorerEx.Utils;
 using ExplorerEx.View.Controls;
 
-namespace ExplorerEx.Model; 
+namespace ExplorerEx.Model;
 
 /// <summary>
 /// 所有可以显示在<see cref="FileListView"/>中的项目的基类
 /// </summary>
 public abstract class FileListViewItem : INotifyPropertyChanged {
-	protected FileListViewItem(string fullPath, string name) {
+	protected FileListViewItem(string fullPath, string name, bool isFolder) {
 		FullPath = fullPath;
 		Name = name;
+		defaultIcon = isFolder ? IconHelper.FolderDrawingImage : IconHelper.UnknownFileDrawingImage;
+		This = this;
+	}
+
+	protected FileListViewItem(string fullPath, string name, ImageSource defaultIcon) {
+		FullPath = fullPath;
+		Name = name;
+		this.defaultIcon = defaultIcon;
 		This = this;
 	}
 
@@ -30,7 +38,13 @@ public abstract class FileListViewItem : INotifyPropertyChanged {
 	/// </summary>
 	[NotMapped]
 	public ImageSource? Icon {
-		get => icon;
+		get {
+			if (icon != null) {
+				return icon;
+			}
+			Task.Run(() => LoadIcon(LoadDetailsOptions.Default));
+			return defaultIcon;
+		}
 		protected set {
 			if (icon != value) {
 				icon = value;
@@ -41,8 +55,10 @@ public abstract class FileListViewItem : INotifyPropertyChanged {
 
 	private ImageSource? icon;
 
+	protected readonly ImageSource defaultIcon;
+
 	[Key]
-	public string FullPath { get; protected set; }
+	public string FullPath { get; protected init; }
 
 	public abstract string DisplayText { get; }
 
@@ -139,7 +155,19 @@ public abstract class FileListViewItem : INotifyPropertyChanged {
 	#endregion
 
 	public override string ToString() {
-		return DisplayText;
+		return FullPath;
+	}
+
+	public override int GetHashCode() {
+		return FullPath.GetHashCode();
+	}
+
+	public override bool Equals(object? other) {
+		return other is FileListViewItem i && i.FullPath == FullPath;
+	}
+
+	public bool Equals(FileListViewItem other) {
+		return other.FullPath == FullPath;
 	}
 
 	/// <summary>
@@ -149,32 +177,46 @@ public abstract class FileListViewItem : INotifyPropertyChanged {
 	/// <param name="token"></param>
 	/// <param name="options"></param>
 	/// <returns></returns>
-	public static async Task LoadDetails(IReadOnlyCollection<FileListViewItem> list, CancellationToken token, LoadDetailsOptions options) {
-		try {
-			if (list.Count > 0) {
-				await Task.WhenAll(Partitioner.Create(list).GetPartitions(4).Select(partition => Task.Run(() => {
+	public static async Task LoadDetails(IReadOnlyCollection<FileListViewItem>? list, LoadDetailsOptions options, CancellationToken token) {
+		if (list is { Count: > 0 }) {
+			try {
+				var tasks = Partitioner.Create(list).GetPartitions(Math.Max(App.ProcessorCount, 2)).Select(partition => Task.Run(() => {
 					if (token.IsCancellationRequested) {
 						return Task.FromCanceled(token);
 					}
 					using (partition) {
 						while (partition.MoveNext()) {
-							var item = partition.Current!;
-							item.LoadAttributes(options);
-							item.LoadIcon(options);
-
 							if (token.IsCancellationRequested) {
 								return Task.FromCanceled(token);
 							}
+
+							partition.Current.LoadAttributes(options);
 						}
 					}
 
 					return Task.CompletedTask;
-				}, token)));
+				}, token));
+
+				if (options.PreLoadIcon) {
+					tasks = tasks.Append(Task.Run(() => {
+						foreach (var item in list) {
+							if (token.IsCancellationRequested) {
+								return Task.FromCanceled(token);
+							}
+
+							item.LoadIcon(options);
+						}
+
+						return Task.CompletedTask;
+					}, token));
+				}
+
+				await Task.WhenAll(tasks);
+			} catch (TaskCanceledException) {
+				// Ignore
+			} catch (Exception e) {
+				Logger.Exception(e);
 			}
-		} catch (TaskCanceledException) {
-			// Ignore
-		} catch (Exception e) {
-			Logger.Exception(e);
 		}
 	}
 
@@ -184,10 +226,17 @@ public abstract class FileListViewItem : INotifyPropertyChanged {
 	/// </summary>
 	public class LoadDetailsOptions {
 		public static LoadDetailsOptions Default { get; } = new() {
+			PreLoadIcon = true,
 			UseLargeIcon = false
 		};
 
+		public bool PreLoadIcon { get; set; }
+
 		public bool UseLargeIcon { get; set; }
+
+		public void SetPreLoadIconByItemCount(int count) {
+			PreLoadIcon = count / App.ProcessorCount < 20;
+		}
 	}
 
 	/// <summary>

ExplorerEx/Model/FileItem/FileSystemItem.cs

@@ -1,8 +1,10 @@
 using System;
 using System.Collections.Generic;
+using System.Diagnostics;
 using System.IO;
 using System.Linq;
 using System.Threading;
+using System.Windows.Media;
 using ExplorerEx.Shell32;
 using ExplorerEx.Utils;
 using static ExplorerEx.Utils.IconHelper;
@@ -24,7 +26,7 @@ public abstract class FileSystemItem : FileListViewItem {
 		}
 	}
 
-	private DateTime dateModified;
+	private DateTime dateModified = DateTime.MaxValue;
 
 	/// <summary>
 	/// 自动更新UI
@@ -39,16 +41,13 @@ public abstract class FileSystemItem : FileListViewItem {
 		}
 	}
 
-	private DateTime dateCreated;
+	private DateTime dateCreated = DateTime.MaxValue;
 
 	public override string GetRenameName() {
 		return Name;
 	}
 
 	protected override bool InternalRename(string newName) {
-		if (newName == null) {
-			return false;
-		}
 		var basePath = Path.GetDirectoryName(FullPath);
 		if (Path.GetExtension(FullPath) != Path.GetExtension(newName)) {
 			if (!MessageBoxHelper.AskWithDefault("RenameExtension", "#AreYouSureToChangeExtension".L())) {
@@ -75,7 +74,9 @@ public abstract class FileSystemItem : FileListViewItem {
 		LoadAttributes(options);
 	}
 
-	protected FileSystemItem(string fullPath, string name) : base(fullPath, name) { }
+	protected FileSystemItem(string fullPath, string name, bool isFolder) : base(fullPath, name, isFolder) { }
+
+	protected FileSystemItem(string fullPath, string name, ImageSource defaultIcon) : base(fullPath, name, defaultIcon) { }
 }
 
 public class FileItem : FileSystemItem {
@@ -100,13 +101,12 @@ public class FileItem : FileSystemItem {
 
 	public override string DisplayText => Name;
 
-	protected FileItem() : base(null!, null!) { }
+	protected FileItem() : base(null!, null!, false) { }
 
-	public FileItem(FileInfo fileInfo) : base(fileInfo.FullName, fileInfo.Name) {
+	public FileItem(FileInfo fileInfo) : base(fileInfo.FullName, fileInfo.Name, false) {
 		FileInfo = fileInfo;
 		IsFolder = false;
 		FileSize = -1;
-		Icon = UnknownFileDrawingImage;
 	}
 
 	public override void LoadAttributes(LoadDetailsOptions options) {
@@ -186,25 +186,26 @@ public class FolderItem : FileSystemItem {
 
 	private bool isEmptyFolder;
 
-	protected FolderItem() : base(null!, null!) { }
+	protected FolderItem() : base(null!, null!, true) { }
 
-	public FolderItem(string fullPath): base(fullPath, Path.GetFileName(fullPath)) {
+	public FolderItem(string fullPath): base(fullPath, Path.GetFileName(fullPath), InitializeIsEmptyFolder(fullPath)) {
 		IsFolder = true;
 		FileSize = -1;
+	}
+
+	protected static ImageSource InitializeIsEmptyFolder(string fullPath) {
 		if (IsEmptyFolderDictionary.TryGetValue(fullPath, out var isEmpty)) {
-			isEmptyFolder = isEmpty;
-			Icon = isEmpty ? EmptyFolderDrawingImage : FolderDrawingImage;
-		} else {
-			Icon = FolderDrawingImage;
+			return isEmpty ? EmptyFolderDrawingImage : FolderDrawingImage;
 		}
+		return FolderDrawingImage;
 	}
 
 	public override string DisplayText => Name;
 
 	public override void LoadAttributes(LoadDetailsOptions options) {
 		isEmptyFolder = FolderUtils.IsEmptyFolder(FullPath);
-		Type = isEmptyFolder ? "EmptyFolder".L() : "Folder".L();
 		IsEmptyFolderDictionary.Add(FullPath, isEmptyFolder);
+		Type = isEmptyFolder ? "EmptyFolder".L() : "Folder".L();
 		var directoryInfo = new DirectoryInfo(FullPath);
 		DateModified = directoryInfo.LastWriteTime;
 		DateCreated = directoryInfo.CreationTime;