Add option to not reload assemblies

ILSpy/MainWindow.xaml.cs

@@ -362,15 +362,22 @@ namespace ICSharpCode.ILSpy
 		{
 			ILSpySettings spySettings = this.spySettings;
 			this.spySettings = null;
+			var loadPreviousAssemblies = Options.MiscSettingsPanel.CurrentMiscSettings.LoadPreviousAssemblies;
 
-			// Load AssemblyList only in Loaded event so that WPF is initialized before we start the CPU-heavy stuff.
-			// This makes the UI come up a bit faster.
-			this.assemblyList = assemblyListManager.LoadList(spySettings, sessionSettings.ActiveAssemblyList);
+			if (loadPreviousAssemblies) {
+				// Load AssemblyList only in Loaded event so that WPF is initialized before we start the CPU-heavy stuff.
+				// This makes the UI come up a bit faster.
+				this.assemblyList = assemblyListManager.LoadList(spySettings, sessionSettings.ActiveAssemblyList);
+			} else {
+				this.assemblyList = new AssemblyList(AssemblyListManager.DefaultListName);
+				assemblyListManager.ClearAll();
+			}
 
 			HandleCommandLineArguments(App.CommandLineArguments);
 
 			if (assemblyList.GetAssemblies().Length == 0
-				&& assemblyList.ListName == AssemblyListManager.DefaultListName) {
+				&& assemblyList.ListName == AssemblyListManager.DefaultListName
+				&& loadPreviousAssemblies) {
 				LoadInitialAssemblies();
 			}
 
@@ -731,7 +738,7 @@ namespace ICSharpCode.ILSpy
 				OpenFiles(dlg.FileNames);
 			}
 		}
-		
+
 		public void OpenFiles(string[] fileNames, bool focusNode = true)
 		{
 			if (fileNames == null)

ILSpy/Options/MiscSettings.cs

@@ -24,6 +24,7 @@ namespace ICSharpCode.ILSpy.Options
 	public class MiscSettings : INotifyPropertyChanged
 	{
 		bool allowMultipleInstances;
+		bool loadPreviousAssemblies;
 
 		/// <summary>
 		/// Allow multiple instances.
@@ -39,6 +40,19 @@ namespace ICSharpCode.ILSpy.Options
 			}
 		}
 
+		/// <summary>
+		/// Load assemblies that were loaded in the previous instance
+		/// </summary>
+		public bool LoadPreviousAssemblies {
+			get { return loadPreviousAssemblies; }
+			set {
+				if (loadPreviousAssemblies != value) {
+					loadPreviousAssemblies = value;
+					OnPropertyChanged();
+				}
+			}
+		}
+
 		#region INotifyPropertyChanged Implementation
 
 		public event PropertyChangedEventHandler PropertyChanged;

ILSpy/Options/MiscSettingsPanel.xaml

@@ -7,5 +7,6 @@
              d:DesignHeight="300" d:DesignWidth="300">
 	<StackPanel Margin="10">
 		<CheckBox IsChecked="{Binding AllowMultipleInstances}">Allow multiple instances</CheckBox>
+		<CheckBox IsChecked="{Binding LoadPreviousAssemblies}">Load assemblies that were loaded in the last instance.</CheckBox>
 	</StackPanel>
 </UserControl>

ILSpy/Options/MiscSettingsPanel.xaml.cs

@@ -50,6 +50,8 @@ namespace ICSharpCode.ILSpy.Options
 			XElement e = settings["MiscSettings"];
 			var s = new MiscSettings();
 			s.AllowMultipleInstances = (bool?)e.Attribute("AllowMultipleInstances") ?? false;
+			s.LoadPreviousAssemblies = (bool?)e.Attribute(nameof(s.LoadPreviousAssemblies)) ?? true;
+
 			return s;
 		}
 
@@ -59,6 +61,7 @@ namespace ICSharpCode.ILSpy.Options
 
 			var section = new XElement("MiscSettings");
 			section.SetAttributeValue("AllowMultipleInstances", s.AllowMultipleInstances);
+			section.SetAttributeValue(nameof(s.LoadPreviousAssemblies), s.LoadPreviousAssemblies);
 
 			XElement existingElement = root.Element("MiscSettings");
 			if (existingElement != null)