diff --git a/OpenRA.Game/Graphics/Viewport.cs b/OpenRA.Game/Graphics/Viewport.cs
index b5661c958e..ac383cc7ee 100755
--- a/OpenRA.Game/Graphics/Viewport.cs
+++ b/OpenRA.Game/Graphics/Viewport.cs
@@ -138,14 +138,22 @@ namespace OpenRA.Graphics
 			return new Rectangle(left, top, right - left, bottom - top);
 		}
 
+		int2 cachedScroll = new int2(int.MaxValue, int.MaxValue);
+		Rectangle cachedRect;
+		
 		public Rectangle WorldBounds(World world)
 		{
-			int2 boundary = new int2(1,1); // Add a curtain of cells around the viewport to account for rounding errors
-			var tl = ViewToWorld(int2.Zero).ToInt2() - boundary;
-			var br = ViewToWorld(new int2(Width, Height)).ToInt2() + boundary;
-			var view = Rectangle.Intersect(Rectangle.FromLTRB(tl.X, tl.Y, br.X, br.Y), world.Map.Bounds);
+			if (cachedScroll != scrollPosition)
+			{
+				int2 boundary = new int2(1,1); // Add a curtain of cells around the viewport to account for rounding errors
+				var tl = ViewToWorld(int2.Zero).ToInt2() - boundary;
+				var br = ViewToWorld(new int2(Width, Height)).ToInt2() + boundary;
+				cachedRect = Rectangle.Intersect(Rectangle.FromLTRB(tl.X, tl.Y, br.X, br.Y), world.Map.Bounds);
+				cachedScroll = scrollPosition;
+			}
+			
 			var b = world.LocalShroud.Bounds;
-			return (b.HasValue) ? Rectangle.Intersect(view, b.Value) : view;
+			return (b.HasValue) ? Rectangle.Intersect(cachedRect, b.Value) : cachedRect;
 		}
 	}
 }
\ No newline at end of file
diff --git a/OpenRA.Game/ShroudRenderer.cs b/OpenRA.Game/ShroudRenderer.cs
index da48af59ea..3c58d2c685 100644
--- a/OpenRA.Game/ShroudRenderer.cs
+++ b/OpenRA.Game/ShroudRenderer.cs
@@ -128,9 +128,11 @@ namespace OpenRA
 			for (var j = clip.Top; j < clip.Bottom; j++)
 			{
 				var starti = clip.Left;
+				var last = shadowBits[0x0f];
 				for (var i = clip.Left; i < clip.Right; i++)
 				{
-					if (s[i, j] == shadowBits[0x0f])
+					if ((s[i, j] == shadowBits[0x0f] && last == shadowBits[0x0f])
+						|| (s[i, j] == shadowBits[0] && last == shadowBits[0]))
 						continue;
 
 					if (starti != i)
@@ -146,6 +148,7 @@ namespace OpenRA
 						Game.CellSize * new float2(i, j),
 						shroudPalette);
 					starti = i + 1;
+					last = s[i, j];
 				}
 
 				if (starti < clip.Right)