diff --git a/OpenRA.Game/Exts.cs b/OpenRA.Game/Exts.cs
index 5244557755..4d2aea2e72 100644
--- a/OpenRA.Game/Exts.cs
+++ b/OpenRA.Game/Exts.cs
@@ -151,6 +151,26 @@ namespace OpenRA
 				return xs.ElementAt(r.Next(xs.Count));
 		}
 
+		public static Rectangle Union(this IEnumerable<Rectangle> rects)
+		{
+			// PERF: Avoid LINQ.
+			var first = true;
+			var result = Rectangle.Empty;
+			foreach (var rect in rects)
+			{
+				if (first)
+				{
+					first = false;
+					result = rect;
+					continue;
+				}
+
+				result = Rectangle.Union(rect, result);
+			}
+
+			return result;
+		}
+
 		public static float Product(this IEnumerable<float> xs)
 		{
 			return xs.Aggregate(1f, (a, x) => a * x);
diff --git a/OpenRA.Game/Traits/World/ScreenMap.cs b/OpenRA.Game/Traits/World/ScreenMap.cs
index 9cc3672fb8..93d6876ebf 100644
--- a/OpenRA.Game/Traits/World/ScreenMap.cs
+++ b/OpenRA.Game/Traits/World/ScreenMap.cs
@@ -219,31 +219,6 @@ namespace OpenRA.Traits
 			return partitionedRenderableFrozenActors[p].InBox(RectWithCorners(a, b)).Where(frozenActorIsValid);
 		}
 
-		Rectangle AggregateBounds(IEnumerable<Rectangle> screenBounds)
-		{
-			if (!screenBounds.Any())
-				return Rectangle.Empty;
-
-			var bounds = screenBounds.First();
-			foreach (var b in screenBounds.Skip(1))
-				bounds = Rectangle.Union(bounds, b);
-
-			return bounds;
-		}
-
-		Rectangle AggregateBounds(IEnumerable<int2> vertices)
-		{
-			if (!vertices.Any())
-				return Rectangle.Empty;
-
-			var first = vertices.First();
-			var rect = new Rectangle(first.X, first.Y, 0, 0);
-			foreach (var v in vertices.Skip(1))
-				rect = Rectangle.Union(rect, new Rectangle(v.X, v.Y, 0, 0));
-
-			return rect;
-		}
-
 		public void TickRender()
 		{
 			foreach (var a in addOrUpdateActors)
@@ -261,7 +236,7 @@ namespace OpenRA.Traits
 				else
 					partitionedMouseActors.Remove(a);
 
-				var screenBounds = AggregateBounds(a.ScreenBounds(worldRenderer));
+				var screenBounds = a.ScreenBounds(worldRenderer).Union();
 				if (!screenBounds.Size.IsEmpty)
 				{
 					if (partitionedRenderableActors.Contains(a))
@@ -298,7 +273,7 @@ namespace OpenRA.Traits
 					else
 						partitionedMouseFrozenActors[kv.Key].Remove(fa);
 
-					var screenBounds = AggregateBounds(fa.ScreenBounds);
+					var screenBounds = fa.ScreenBounds.Union();
 					if (!screenBounds.Size.IsEmpty)
 					{
 						if (partitionedRenderableFrozenActors[kv.Key].Contains(fa))
diff --git a/OpenRA.Mods.Common/Graphics/DefaultSpriteSequence.cs b/OpenRA.Mods.Common/Graphics/DefaultSpriteSequence.cs
index 8a84f87a66..9f3491635e 100644
--- a/OpenRA.Mods.Common/Graphics/DefaultSpriteSequence.cs
+++ b/OpenRA.Mods.Common/Graphics/DefaultSpriteSequence.cs
@@ -324,12 +324,7 @@ namespace OpenRA.Mods.Common.Graphics
 				if (ShadowStart > 0)
 					boundSprites = boundSprites.Concat(SpriteBounds(sprites, Frames, ShadowStart, Facings, Length, Stride, transpose));
 
-				if (boundSprites.Any())
-				{
-					Bounds = boundSprites.First();
-					foreach (var b in boundSprites.Skip(1))
-						Bounds = Rectangle.Union(Bounds, b);
-				}
+				Bounds = boundSprites.Union();
 			}
 			catch (FormatException f)
 			{
diff --git a/OpenRA.Mods.Common/Traits/World/EditorActorPreview.cs b/OpenRA.Mods.Common/Traits/World/EditorActorPreview.cs
index a039452a22..942fdbf2a3 100644
--- a/OpenRA.Mods.Common/Traits/World/EditorActorPreview.cs
+++ b/OpenRA.Mods.Common/Traits/World/EditorActorPreview.cs
@@ -92,12 +92,7 @@ namespace OpenRA.Mods.Common.Traits
 			// If this is a problem, then we may need to fetch the area from somewhere else
 			var r = previews.SelectMany(p => p.ScreenBounds(worldRenderer, CenterPosition));
 
-			if (r.Any())
-			{
-				Bounds = r.First();
-				foreach (var rr in r.Skip(1))
-					Bounds = Rectangle.Union(Bounds, rr);
-			}
+			Bounds = r.Union();
 
 			SelectionBox = new SelectionBoxRenderable(new WPos(CenterPosition.X, CenterPosition.Y, 8192),
 				new Rectangle(Bounds.X, Bounds.Y, Bounds.Width, Bounds.Height), Color.White);
diff --git a/OpenRA.Mods.Common/Widgets/ActorPreviewWidget.cs b/OpenRA.Mods.Common/Widgets/ActorPreviewWidget.cs
index f7923729a7..154eb8a5aa 100644
--- a/OpenRA.Mods.Common/Widgets/ActorPreviewWidget.cs
+++ b/OpenRA.Mods.Common/Widgets/ActorPreviewWidget.cs
@@ -53,20 +53,10 @@ namespace OpenRA.Mods.Common.Widgets
 				.ToArray();
 
 			// Calculate the preview bounds
-			PreviewOffset = int2.Zero;
-			IdealPreviewSize = int2.Zero;
-
 			var r = preview.SelectMany(p => p.ScreenBounds(worldRenderer, WPos.Zero));
-
-			if (r.Any())
-			{
-				var b = r.First();
-				foreach (var rr in r.Skip(1))
-					b = Rectangle.Union(b, rr);
-
-				IdealPreviewSize = new int2(b.Width, b.Height);
-				PreviewOffset = -new int2(b.Left, b.Top) - IdealPreviewSize / 2;
-			}
+			var b = r.Union();
+			IdealPreviewSize = new int2(b.Width, b.Height);
+			PreviewOffset = -new int2(b.Left, b.Top) - IdealPreviewSize / 2;
 		}
 
 		IFinalizedRenderable[] renderables;
diff --git a/OpenRA.Mods.Common/Widgets/ProductionPaletteWidget.cs b/OpenRA.Mods.Common/Widgets/ProductionPaletteWidget.cs
index 7d1031964a..d5e6dcbe58 100644
--- a/OpenRA.Mods.Common/Widgets/ProductionPaletteWidget.cs
+++ b/OpenRA.Mods.Common/Widgets/ProductionPaletteWidget.cs
@@ -425,7 +425,7 @@ namespace OpenRA.Mods.Common.Widgets
 				DisplayedIconCount++;
 			}
 
-			eventBounds = icons.Any() ? icons.Keys.Aggregate(Rectangle.Union) : Rectangle.Empty;
+			eventBounds = icons.Keys.Union();
 
 			if (oldIconCount != DisplayedIconCount)
 				OnIconCountChanged(oldIconCount, DisplayedIconCount);
diff --git a/OpenRA.Mods.Common/Widgets/SupportPowersWidget.cs b/OpenRA.Mods.Common/Widgets/SupportPowersWidget.cs
index 91a0d36424..a6f1720e94 100644
--- a/OpenRA.Mods.Common/Widgets/SupportPowersWidget.cs
+++ b/OpenRA.Mods.Common/Widgets/SupportPowersWidget.cs
@@ -154,7 +154,7 @@ namespace OpenRA.Mods.Common.Widgets
 				IconCount++;
 			}
 
-			eventBounds = icons.Any() ? icons.Keys.Aggregate(Rectangle.Union) : Rectangle.Empty;
+			eventBounds = icons.Keys.Union();
 
 			if (oldIconCount != IconCount)
 				OnIconCountChanged(oldIconCount, IconCount);