diff --git a/VirtualListView/Controls/VirtualListView.cs b/VirtualListView/Controls/VirtualListView.cs
index cb890bf..3052297 100644
--- a/VirtualListView/Controls/VirtualListView.cs
+++ b/VirtualListView/Controls/VirtualListView.cs
@@ -247,20 +247,20 @@ public ICommand? ScrolledCommand
 	}
 
 	public static readonly BindableProperty SelectedItemsProperty =
-		BindableProperty.Create(nameof(SelectedItems), typeof(IList<ItemPosition>), typeof(VirtualListView), Array.Empty<ItemPosition>(),
+		BindableProperty.Create(nameof(SelectedItems), typeof(ISet<ItemPosition>), typeof(VirtualListView), new HashSet<ItemPosition>(),
 			propertyChanged: (bindableObj, oldValue, newValue) =>
 			{
 				if (bindableObj is VirtualListView vlv
-					&& oldValue is IList<ItemPosition> oldSelection
-					&& newValue is IList<ItemPosition> newSelection)
+					&& oldValue is ISet<ItemPosition> oldSelection
+					&& newValue is ISet<ItemPosition> newSelection)
 				{
 					vlv.RaiseSelectedItemsChanged(oldSelection.ToArray(), newSelection.ToArray());
 				}
 			});
-	public IList<ItemPosition>? SelectedItems
+	public ISet<ItemPosition>? SelectedItems
 	{
-		get => (IList<ItemPosition>)GetValue(SelectedItemsProperty);
-		set => SetValue(SelectedItemsProperty, value ?? Array.Empty<ItemPosition>());
+		get => (ISet<ItemPosition>?)GetValue(SelectedItemsProperty);
+		set => SetValue(SelectedItemsProperty, value ?? new HashSet<ItemPosition>());
 	}
 
 	public static readonly BindableProperty SelectedItemProperty =
@@ -272,7 +272,7 @@ public IList<ItemPosition>? SelectedItems
 					if (newValue is null || newValue is not ItemPosition)
 						vlv.SelectedItems = null;
 					else if (newValue is ItemPosition p)
-						vlv.SelectedItems = new[] { p };
+						vlv.SelectedItems = new HashSet<ItemPosition>(){p};
 				}
 			});
 
@@ -294,11 +294,11 @@ public void DeselectItem(ItemPosition itemPosition)
 		}
 		else if (SelectionMode == Maui.SelectionMode.Multiple)
 		{
-			var current = SelectedItems.ToList();
-			if (current.Contains(itemPosition))
+			if (SelectedItems?.Contains(itemPosition) ?? false)
 			{
+				var current = SelectedItems.ToHashSet();
 				current.Remove(itemPosition);
-				SelectedItems = current.ToArray();
+				SelectedItems = current;
 			}
 		}
 	}
@@ -314,10 +314,26 @@ public void SelectItem(ItemPosition itemPosition)
 		}
 		else if (SelectionMode == Maui.SelectionMode.Multiple)
 		{
-			var current = SelectedItems;
-			if (current is null || !current.Contains(itemPosition))
+			if (!(SelectedItems?.Contains(itemPosition) ?? false))
 			{
-				SelectedItems = (current ?? []).Append(itemPosition).ToArray();
+				var current = SelectedItems?.ToHashSet() ?? [];
+				current.Add(itemPosition);
+				SelectedItems = current;
+			}
+		}
+	}
+
+	public void SelectMany(IEnumerable<ItemPosition> items)
+	{
+		if (SelectionMode == Maui.SelectionMode.Multiple)
+		{
+			if (items.Any(i => !(SelectedItems?.Contains(i) ?? false)))
+			{
+				var current = (SelectedItems ?? Enumerable.Empty<ItemPosition>())
+						.Concat(items)
+						.ToHashSet();
+				
+				SelectedItems = current;
 			}
 		}
 	}
diff --git a/VirtualListView/IVirtualListView.cs b/VirtualListView/IVirtualListView.cs
index 8d739e7..f45514d 100644
--- a/VirtualListView/IVirtualListView.cs
+++ b/VirtualListView/IVirtualListView.cs
@@ -22,7 +22,7 @@ public interface IVirtualListView : IView
 
 	SelectionMode SelectionMode { get; }
 
-	IList<ItemPosition> SelectedItems { get; set; }
+	ISet<ItemPosition> SelectedItems { get; set; }
 
 	ItemPosition? SelectedItem { get; set; }
 	
diff --git a/VirtualListView/ItemPosition.cs b/VirtualListView/ItemPosition.cs
index 68022f9..17872d3 100644
--- a/VirtualListView/ItemPosition.cs
+++ b/VirtualListView/ItemPosition.cs
@@ -15,4 +15,6 @@ public ItemPosition(int sectionIndex = 0, int itemIndex = 0)
 
 	public bool Equals(ItemPosition other)
 		=> SectionIndex == other.SectionIndex && ItemIndex == other.ItemIndex;
+    public override int GetHashCode()
+		=> SectionIndex * 16 + ItemIndex;
 }
\ No newline at end of file
diff --git a/VirtualListView/VirtualListViewHandler.cs b/VirtualListView/VirtualListViewHandler.cs
index 79cf0bd..a758c8a 100644
--- a/VirtualListView/VirtualListViewHandler.cs
+++ b/VirtualListView/VirtualListViewHandler.cs
@@ -97,36 +97,33 @@ public bool IsItemSelected(int sectionIndex, int itemIndex)
 		return previousSelections.Contains(new ItemPosition(sectionIndex, itemIndex));
 	}
 
-	ItemPosition[] previousSelections = Array.Empty<ItemPosition>();
+	HashSet<ItemPosition> previousSelections = [];
 
 	public static void MapSelectedItems(VirtualListViewHandler handler, IVirtualListView virtualListView)
 	{
 		if (handler is null)
 			return;
 
-		var newSelections = virtualListView?.SelectedItems ?? Array.Empty<ItemPosition>();
+		ISet<ItemPosition> newSelections = virtualListView?.SelectedItems ?? new HashSet<ItemPosition>();
 
 		if (virtualListView.SelectionMode == SelectionMode.None)
-			newSelections = Array.Empty<ItemPosition>();
+			newSelections = new HashSet<ItemPosition>();
 		else if (virtualListView.SelectionMode == SelectionMode.Single && newSelections.Count > 1)
-			newSelections = newSelections.Take(1).ToArray();
+			newSelections = newSelections.Take(1).ToHashSet();
 
-		// First deselect any previously selected items that aren't in the new set
-		foreach (var itemPosition in handler.previousSelections)
+		var changed = new HashSet<ItemPosition>(handler.previousSelections);
+		changed.SymmetricExceptWith(newSelections);
+		foreach (var itemPosition in changed)
 		{
-			if (!newSelections.Contains(itemPosition))
+			if (handler.previousSelections.Contains(itemPosition))
+				// Deselect any previously selected items that aren't in the new set
 				handler.PlatformUpdateItemSelection(itemPosition, false);
-		}
-
-		// Set all the new state selected to true
-		foreach (var itemPosition in newSelections)
-		{
-			if (!handler.previousSelections.Contains(itemPosition))
+			else 
+				// Set all the new state selected to true
 				handler.PlatformUpdateItemSelection(itemPosition, true);
 		}
-
 		// Keep track of the new state for next time it changes
-		handler.previousSelections = newSelections.ToArray();
+		handler.previousSelections = new HashSet<ItemPosition>(newSelections);
 	}
 
 	public static void MapIsHeaderVisible(VirtualListViewHandler handler, IVirtualListView virtualListView)