diff --git a/OpenRA.Game/Graphics/Renderable.cs b/OpenRA.Game/Graphics/Renderable.cs
index 819602581b..ddf1c1fc9e 100644
--- a/OpenRA.Game/Graphics/Renderable.cs
+++ b/OpenRA.Game/Graphics/Renderable.cs
@@ -30,7 +30,7 @@ namespace OpenRA.Graphics
 
 	public interface ITintableRenderable
 	{
-		IRenderable WithTint(float3 newTint);
+		IRenderable WithTint(in float3 newTint);
 	}
 
 	public interface IFinalizedRenderable
diff --git a/OpenRA.Game/Graphics/RgbaColorRenderer.cs b/OpenRA.Game/Graphics/RgbaColorRenderer.cs
index c129c6d1ee..796138c465 100644
--- a/OpenRA.Game/Graphics/RgbaColorRenderer.cs
+++ b/OpenRA.Game/Graphics/RgbaColorRenderer.cs
@@ -28,7 +28,7 @@ namespace OpenRA.Graphics
 			this.parent = parent;
 		}
 
-		public void DrawLine(float3 start, float3 end, float width, Color startColor, Color endColor)
+		public void DrawLine(in float3 start, in float3 end, float width, Color startColor, Color endColor)
 		{
 			var delta = (end - start) / (end - start).XY.Length;
 			var corner = width / 2 * new float3(-delta.Y, delta.X, delta.Z);
@@ -55,7 +55,7 @@ namespace OpenRA.Graphics
 			parent.DrawRGBAVertices(vertices);
 		}
 
-		public void DrawLine(float3 start, float3 end, float width, Color color)
+		public void DrawLine(in float3 start, in float3 end, float width, Color color)
 		{
 			var delta = (end - start) / (end - start).XY.Length;
 			var corner = width / 2 * new float2(-delta.Y, delta.X);
@@ -80,7 +80,7 @@ namespace OpenRA.Graphics
 		/// Will behave badly if the lines are parallel.
 		/// Z position is the average of a and b (ignores actual intersection point if it exists)
 		/// </summary>
-		float3 IntersectionOf(float3 a, float3 da, float3 b, float3 db)
+		float3 IntersectionOf(in float3 a, in float3 da, in float3 b, in float3 db)
 		{
 			var crossA = a.X * (a.Y + da.Y) - a.Y * (a.X + da.X);
 			var crossB = b.X * (b.Y + db.Y) - b.Y * (b.X + db.X);
@@ -193,14 +193,14 @@ namespace OpenRA.Graphics
 			DrawConnectedLine(vertices.Select(v => new float3(v, 0)).ToArray(), width, color, true);
 		}
 
-		public void DrawRect(float3 tl, float3 br, float width, Color color)
+		public void DrawRect(in float3 tl, in float3 br, float width, Color color)
 		{
 			var tr = new float3(br.X, tl.Y, tl.Z);
 			var bl = new float3(tl.X, br.Y, br.Z);
 			DrawPolygon(new[] { tl, tr, br, bl }, width, color);
 		}
 
-		public void FillTriangle(float3 a, float3 b, float3 c, Color color)
+		public void FillTriangle(in float3 a, in float3 b, in float3 c, Color color)
 		{
 			color = Util.PremultiplyAlpha(color);
 			var cr = color.R / 255.0f;
@@ -214,14 +214,14 @@ namespace OpenRA.Graphics
 			parent.DrawRGBAVertices(vertices);
 		}
 
-		public void FillRect(float3 tl, float3 br, Color color)
+		public void FillRect(in float3 tl, in float3 br, Color color)
 		{
 			var tr = new float3(br.X, tl.Y, tl.Z);
 			var bl = new float3(tl.X, br.Y, br.Z);
 			FillRect(tl, tr, br, bl, color);
 		}
 
-		public void FillRect(float3 a, float3 b, float3 c, float3 d, Color color)
+		public void FillRect(in float3 a, in float3 b, in float3 c, in float3 d, Color color)
 		{
 			color = Util.PremultiplyAlpha(color);
 			var cr = color.R / 255.0f;
@@ -238,7 +238,7 @@ namespace OpenRA.Graphics
 			parent.DrawRGBAVertices(vertices);
 		}
 
-		public void FillRect(float3 a, float3 b, float3 c, float3 d, Color topLeftColor, Color topRightColor, Color bottomRightColor, Color bottomLeftColor)
+		public void FillRect(in float3 a, in float3 b, in float3 c, in float3 d, Color topLeftColor, Color topRightColor, Color bottomRightColor, Color bottomLeftColor)
 		{
 			vertices[0] = VertexWithColor(a + Offset, topLeftColor);
 			vertices[1] = VertexWithColor(b + Offset, topRightColor);
@@ -250,7 +250,7 @@ namespace OpenRA.Graphics
 			parent.DrawRGBAVertices(vertices);
 		}
 
-		static Vertex VertexWithColor(float3 xyz, Color color)
+		static Vertex VertexWithColor(in float3 xyz, Color color)
 		{
 			color = Util.PremultiplyAlpha(color);
 			var cr = color.R / 255.0f;
@@ -261,7 +261,7 @@ namespace OpenRA.Graphics
 			return new Vertex(xyz, cr, cg, cb, ca, 0, 0);
 		}
 
-		public void FillEllipse(float3 tl, float3 br, Color color, int vertices = 32)
+		public void FillEllipse(in float3 tl, in float3 br, Color color, int vertices = 32)
 		{
 			// TODO: Create an ellipse polygon instead
 			var a = (br.X - tl.X) / 2;
diff --git a/OpenRA.Game/Graphics/RgbaSpriteRenderer.cs b/OpenRA.Game/Graphics/RgbaSpriteRenderer.cs
index 21f1b980c9..eca37f72b3 100644
--- a/OpenRA.Game/Graphics/RgbaSpriteRenderer.cs
+++ b/OpenRA.Game/Graphics/RgbaSpriteRenderer.cs
@@ -22,7 +22,7 @@ namespace OpenRA.Graphics
 			this.parent = parent;
 		}
 
-		public void DrawSprite(Sprite s, float3 location, float3 size)
+		public void DrawSprite(Sprite s, in float3 location, in float3 size)
 		{
 			if (s.Channel != TextureChannel.RGBA)
 				throw new InvalidOperationException("DrawRGBASprite requires a RGBA sprite.");
@@ -30,7 +30,7 @@ namespace OpenRA.Graphics
 			parent.DrawSprite(s, location, 0, size);
 		}
 
-		public void DrawSprite(Sprite s, float3 location)
+		public void DrawSprite(Sprite s, in float3 location)
 		{
 			if (s.Channel != TextureChannel.RGBA)
 				throw new InvalidOperationException("DrawRGBASprite requires a RGBA sprite.");
@@ -38,7 +38,7 @@ namespace OpenRA.Graphics
 			parent.DrawSprite(s, location, 0, s.Size);
 		}
 
-		public void DrawSprite(Sprite s, float3 a, float3 b, float3 c, float3 d)
+		public void DrawSprite(Sprite s, in float3 a, in float3 b, in float3 c, in float3 d)
 		{
 			if (s.Channel != TextureChannel.RGBA)
 				throw new InvalidOperationException("DrawRGBASprite requires a RGBA sprite.");
@@ -46,7 +46,7 @@ namespace OpenRA.Graphics
 			parent.DrawSprite(s, a, b, c, d);
 		}
 
-		public void DrawSpriteWithTint(Sprite s, float3 location, float3 size, float3 tint)
+		public void DrawSpriteWithTint(Sprite s, in float3 location, in float3 size, in float3 tint)
 		{
 			if (s.Channel != TextureChannel.RGBA)
 				throw new InvalidOperationException("DrawRGBASprite requires a RGBA sprite.");
@@ -54,7 +54,7 @@ namespace OpenRA.Graphics
 			parent.DrawSpriteWithTint(s, location, 0, size, tint);
 		}
 
-		public void DrawSpriteWithTint(Sprite s, float3 a, float3 b, float3 c, float3 d, float3 tint)
+		public void DrawSpriteWithTint(Sprite s, in float3 a, in float3 b, in float3 c, in float3 d, in float3 tint)
 		{
 			if (s.Channel != TextureChannel.RGBA)
 				throw new InvalidOperationException("DrawRGBASprite requires a RGBA sprite.");
diff --git a/OpenRA.Game/Graphics/SheetBuilder.cs b/OpenRA.Game/Graphics/SheetBuilder.cs
index ca0578e453..474a9f3f61 100644
--- a/OpenRA.Game/Graphics/SheetBuilder.cs
+++ b/OpenRA.Game/Graphics/SheetBuilder.cs
@@ -76,7 +76,7 @@ namespace OpenRA.Graphics
 
 		public Sprite Add(ISpriteFrame frame) { return Add(frame.Data, frame.Size, 0, frame.Offset); }
 		public Sprite Add(byte[] src, Size size) { return Add(src, size, 0, float3.Zero); }
-		public Sprite Add(byte[] src, Size size, float zRamp, float3 spriteOffset)
+		public Sprite Add(byte[] src, Size size, float zRamp, in float3 spriteOffset)
 		{
 			// Don't bother allocating empty sprites
 			if (size.Width == 0 || size.Height == 0)
@@ -115,7 +115,7 @@ namespace OpenRA.Graphics
 		}
 
 		public Sprite Allocate(Size imageSize, float scale = 1f) { return Allocate(imageSize, 0, float3.Zero, scale); }
-		public Sprite Allocate(Size imageSize, float zRamp, float3 spriteOffset, float scale = 1f)
+		public Sprite Allocate(Size imageSize, float zRamp, in float3 spriteOffset, float scale = 1f)
 		{
 			if (imageSize.Width + p.X + margin > current.Size.Width)
 			{
diff --git a/OpenRA.Game/Graphics/Sprite.cs b/OpenRA.Game/Graphics/Sprite.cs
index 897c340d0c..102fce3dd9 100644
--- a/OpenRA.Game/Graphics/Sprite.cs
+++ b/OpenRA.Game/Graphics/Sprite.cs
@@ -29,7 +29,7 @@ namespace OpenRA.Graphics
 		public Sprite(Sheet sheet, Rectangle bounds, TextureChannel channel, float scale = 1)
 			: this(sheet, bounds, 0, float2.Zero, channel, BlendMode.Alpha, scale) { }
 
-		public Sprite(Sheet sheet, Rectangle bounds, float zRamp, float3 offset, TextureChannel channel, BlendMode blendMode = BlendMode.Alpha, float scale = 1f)
+		public Sprite(Sheet sheet, Rectangle bounds, float zRamp, in float3 offset, TextureChannel channel, BlendMode blendMode = BlendMode.Alpha, float scale = 1f)
 		{
 			Sheet = sheet;
 			Bounds = bounds;
diff --git a/OpenRA.Game/Graphics/SpriteRenderable.cs b/OpenRA.Game/Graphics/SpriteRenderable.cs
index 135553c7d9..b3299d8494 100644
--- a/OpenRA.Game/Graphics/SpriteRenderable.cs
+++ b/OpenRA.Game/Graphics/SpriteRenderable.cs
@@ -58,7 +58,7 @@ namespace OpenRA.Graphics
 		public IRenderable OffsetBy(WVec vec) { return new SpriteRenderable(sprite, pos + vec, offset, zOffset, palette, scale, tint, isDecoration, ignoreWorldTint); }
 		public IRenderable AsDecoration() { return new SpriteRenderable(sprite, pos, offset, zOffset, palette, scale, tint, true, ignoreWorldTint); }
 
-		public IRenderable WithTint(float3 newTint) { return new SpriteRenderable(sprite, pos, offset, zOffset, palette, scale, newTint, isDecoration, ignoreWorldTint); }
+		public IRenderable WithTint(in float3 newTint) { return new SpriteRenderable(sprite, pos, offset, zOffset, palette, scale, newTint, isDecoration, ignoreWorldTint); }
 
 		float3 ScreenPosition(WorldRenderer wr)
 		{
diff --git a/OpenRA.Game/Graphics/SpriteRenderer.cs b/OpenRA.Game/Graphics/SpriteRenderer.cs
index 9ba6812f6e..695f3a3680 100644
--- a/OpenRA.Game/Graphics/SpriteRenderer.cs
+++ b/OpenRA.Game/Graphics/SpriteRenderer.cs
@@ -108,43 +108,43 @@ namespace OpenRA.Graphics
 			return new int2(sheetIndex, secondarySheetIndex);
 		}
 
-		internal void DrawSprite(Sprite s, float3 location, float paletteTextureIndex, float3 size)
+		internal void DrawSprite(Sprite s, in float3 location, float paletteTextureIndex, in float3 size)
 		{
 			var samplers = SetRenderStateForSprite(s);
 			Util.FastCreateQuad(vertices, location + s.FractionalOffset * size, s, samplers, paletteTextureIndex, nv, size, float3.Ones);
 			nv += 6;
 		}
 
-		public void DrawSprite(Sprite s, float3 location, PaletteReference pal)
+		public void DrawSprite(Sprite s, in float3 location, PaletteReference pal)
 		{
 			DrawSprite(s, location, pal.TextureIndex, s.Size);
 		}
 
-		public void DrawSprite(Sprite s, float3 location, PaletteReference pal, float3 size)
+		public void DrawSprite(Sprite s, in float3 location, PaletteReference pal, float3 size)
 		{
 			DrawSprite(s, location, pal.TextureIndex, size);
 		}
 
-		public void DrawSprite(Sprite s, float3 a, float3 b, float3 c, float3 d)
+		public void DrawSprite(Sprite s, in float3 a, in float3 b, in float3 c, in float3 d)
 		{
 			var samplers = SetRenderStateForSprite(s);
 			Util.FastCreateQuad(vertices, a, b, c, d, s, samplers, 0, float3.Ones, nv);
 			nv += 6;
 		}
 
-		internal void DrawSpriteWithTint(Sprite s, float3 location, float paletteTextureIndex, float3 size, float3 tint)
+		internal void DrawSpriteWithTint(Sprite s, in float3 location, float paletteTextureIndex, in float3 size, in float3 tint)
 		{
 			var samplers = SetRenderStateForSprite(s);
 			Util.FastCreateQuad(vertices, location + s.FractionalOffset * size, s, samplers, paletteTextureIndex, nv, size, tint);
 			nv += 6;
 		}
 
-		public void DrawSpriteWithTint(Sprite s, float3 location, PaletteReference pal, float3 size, float3 tint)
+		public void DrawSpriteWithTint(Sprite s, in float3 location, PaletteReference pal, in float3 size, in float3 tint)
 		{
 			DrawSpriteWithTint(s, location, pal.TextureIndex, size, tint);
 		}
 
-		public void DrawSpriteWithTint(Sprite s, float3 a, float3 b, float3 c, float3 d, float3 tint)
+		public void DrawSpriteWithTint(Sprite s, in float3 a, in float3 b, in float3 c, in float3 d, in float3 tint)
 		{
 			var samplers = SetRenderStateForSprite(s);
 			Util.FastCreateQuad(vertices, a, b, c, d, s, samplers, 0, tint, nv);
diff --git a/OpenRA.Game/Graphics/TerrainSpriteLayer.cs b/OpenRA.Game/Graphics/TerrainSpriteLayer.cs
index 5794f63834..31ef7fcda6 100644
--- a/OpenRA.Game/Graphics/TerrainSpriteLayer.cs
+++ b/OpenRA.Game/Graphics/TerrainSpriteLayer.cs
@@ -137,7 +137,7 @@ namespace OpenRA.Graphics
 			dirtyRows.Add(uv.V);
 		}
 
-		public void Update(MPos uv, Sprite sprite, float3 pos, bool ignoreTint)
+		public void Update(MPos uv, Sprite sprite, in float3 pos, bool ignoreTint)
 		{
 			if (sprite != null)
 			{
diff --git a/OpenRA.Game/Graphics/Util.cs b/OpenRA.Game/Graphics/Util.cs
index eba67ad7d3..977df163a3 100644
--- a/OpenRA.Game/Graphics/Util.cs
+++ b/OpenRA.Game/Graphics/Util.cs
@@ -20,7 +20,7 @@ namespace OpenRA.Graphics
 		// yes, our channel order is nuts.
 		static readonly int[] ChannelMasks = { 2, 1, 0, 3 };
 
-		public static void FastCreateQuad(Vertex[] vertices, float3 o, Sprite r, int2 samplers, float paletteTextureIndex, int nv, float3 size, float3 tint)
+		public static void FastCreateQuad(Vertex[] vertices, in float3 o, Sprite r, int2 samplers, float paletteTextureIndex, int nv, in float3 size, in float3 tint)
 		{
 			var b = new float3(o.X + size.X, o.Y, o.Z);
 			var c = new float3(o.X + size.X, o.Y + size.Y, o.Z + size.Z);
@@ -29,9 +29,9 @@ namespace OpenRA.Graphics
 		}
 
 		public static void FastCreateQuad(Vertex[] vertices,
-			float3 a, float3 b, float3 c, float3 d,
+			in float3 a, in float3 b, in float3 c, in float3 d,
 			Sprite r, int2 samplers, float paletteTextureIndex,
-			float3 tint, int nv)
+			in float3 tint, int nv)
 		{
 			float sl = 0;
 			float st = 0;
diff --git a/OpenRA.Game/Graphics/Vertex.cs b/OpenRA.Game/Graphics/Vertex.cs
index a434a13872..2b45bdb31a 100644
--- a/OpenRA.Game/Graphics/Vertex.cs
+++ b/OpenRA.Game/Graphics/Vertex.cs
@@ -28,13 +28,13 @@ namespace OpenRA.Graphics
 		// Color tint
 		public readonly float R, G, B;
 
-		public Vertex(float3 xyz, float s, float t, float u, float v, float p, float c)
+		public Vertex(in float3 xyz, float s, float t, float u, float v, float p, float c)
 			: this(xyz.X, xyz.Y, xyz.Z, s, t, u, v, p, c, float3.Ones) { }
 
-		public Vertex(float3 xyz, float s, float t, float u, float v, float p, float c, float3 tint)
+		public Vertex(in float3 xyz, float s, float t, float u, float v, float p, float c, in float3 tint)
 			: this(xyz.X, xyz.Y, xyz.Z, s, t, u, v, p, c, tint.X, tint.Y, tint.Z) { }
 
-		public Vertex(float x, float y, float z, float s, float t, float u, float v, float p, float c, float3 tint)
+		public Vertex(float x, float y, float z, float s, float t, float u, float v, float p, float c, in float3 tint)
 			: this(x, y, z, s, t, u, v, p, c, tint.X, tint.Y, tint.Z) { }
 
 		public Vertex(float x, float y, float z, float s, float t, float u, float v, float p, float c, float r, float g, float b)
diff --git a/OpenRA.Game/Graphics/Viewport.cs b/OpenRA.Game/Graphics/Viewport.cs
index 32fdcf9048..05aacec8ce 100644
--- a/OpenRA.Game/Graphics/Viewport.cs
+++ b/OpenRA.Game/Graphics/Viewport.cs
@@ -314,7 +314,7 @@ namespace OpenRA.Graphics
 
 		public int2 ViewToWorldPx(int2 view) { return (graphicSettings.UIScale / Zoom * view.ToFloat2()).ToInt2() + TopLeft; }
 		public int2 WorldToViewPx(int2 world) { return ((Zoom / graphicSettings.UIScale) * (world - TopLeft).ToFloat2()).ToInt2(); }
-		public int2 WorldToViewPx(float3 world) { return ((Zoom / graphicSettings.UIScale) * (world - TopLeft).XY).ToInt2(); }
+		public int2 WorldToViewPx(in float3 world) { return ((Zoom / graphicSettings.UIScale) * (world - TopLeft).XY).ToInt2(); }
 
 		public void Center(IEnumerable<Actor> actors)
 		{
diff --git a/OpenRA.Game/Primitives/float3.cs b/OpenRA.Game/Primitives/float3.cs
index 9e20a35735..5b87260286 100644
--- a/OpenRA.Game/Primitives/float3.cs
+++ b/OpenRA.Game/Primitives/float3.cs
@@ -17,7 +17,7 @@ namespace OpenRA
 {
 	[SuppressMessage("StyleCop.CSharp.NamingRules", "SA1300:ElementMustBeginWithUpperCaseLetter", Justification = "Mimic a built-in type alias.")]
 	[StructLayout(LayoutKind.Sequential)]
-	public struct float3 : IEquatable<float3>
+	public readonly struct float3 : IEquatable<float3>
 	{
 		public readonly float X, Y, Z;
 		public float2 XY { get { return new float2(X, Y); } }
@@ -28,13 +28,13 @@ namespace OpenRA
 		public static implicit operator float3(int2 src) { return new float3(src.X, src.Y, 0); }
 		public static implicit operator float3(float2 src) { return new float3(src.X, src.Y, 0); }
 
-		public static float3 operator +(float3 a, float3 b) { return new float3(a.X + b.X, a.Y + b.Y, a.Z + b.Z); }
-		public static float3 operator -(float3 a, float3 b) { return new float3(a.X - b.X, a.Y - b.Y, a.Z - b.Z); }
-		public static float3 operator -(float3 a) { return new float3(-a.X, -a.Y, -a.Z); }
-		public static float3 operator *(float3 a, float3 b) { return new float3(a.X * b.X, a.Y * b.Y, a.Z * b.Z); }
-		public static float3 operator *(float a, float3 b) { return new float3(a * b.X, a * b.Y, a * b.Z); }
-		public static float3 operator /(float3 a, float3 b) { return new float3(a.X / b.X, a.Y / b.Y, a.Z / b.Z); }
-		public static float3 operator /(float3 a, float b) { return new float3(a.X / b, a.Y / b, a.Z / b); }
+		public static float3 operator +(in float3 a, in float3 b) { return new float3(a.X + b.X, a.Y + b.Y, a.Z + b.Z); }
+		public static float3 operator -(in float3 a, in float3 b) { return new float3(a.X - b.X, a.Y - b.Y, a.Z - b.Z); }
+		public static float3 operator -(in float3 a) { return new float3(-a.X, -a.Y, -a.Z); }
+		public static float3 operator *(in float3 a, in float3 b) { return new float3(a.X * b.X, a.Y * b.Y, a.Z * b.Z); }
+		public static float3 operator *(float a, in float3 b) { return new float3(a * b.X, a * b.Y, a * b.Z); }
+		public static float3 operator /(in float3 a, in float3 b) { return new float3(a.X / b.X, a.Y / b.Y, a.Z / b.Z); }
+		public static float3 operator /(in float3 a, float b) { return new float3(a.X / b, a.Y / b, a.Z / b); }
 
 		public static float3 Lerp(float3 a, float3 b, float t)
 		{
@@ -44,8 +44,8 @@ namespace OpenRA
 				float2.Lerp(a.Z, b.Z, t));
 		}
 
-		public static bool operator ==(float3 me, float3 other) { return me.X == other.X && me.Y == other.Y && me.Z == other.Z; }
-		public static bool operator !=(float3 me, float3 other) { return !(me == other); }
+		public static bool operator ==(in float3 me, in float3 other) { return me.X == other.X && me.Y == other.Y && me.Z == other.Z; }
+		public static bool operator !=(in float3 me, in float3 other) { return !(me == other); }
 		public override int GetHashCode() { return X.GetHashCode() ^ Y.GetHashCode() ^ Z.GetHashCode(); }
 
 		public bool Equals(float3 other)
diff --git a/OpenRA.Mods.Common/Graphics/ModelRenderable.cs b/OpenRA.Mods.Common/Graphics/ModelRenderable.cs
index 1b34236543..7c91209ac9 100644
--- a/OpenRA.Mods.Common/Graphics/ModelRenderable.cs
+++ b/OpenRA.Mods.Common/Graphics/ModelRenderable.cs
@@ -45,7 +45,7 @@ namespace OpenRA.Mods.Common.Graphics
 			IEnumerable<ModelAnimation> models, WPos pos, int zOffset, in WRot camera, float scale,
 			in WRot lightSource, float[] lightAmbientColor, float[] lightDiffuseColor,
 			PaletteReference color, PaletteReference normals, PaletteReference shadow,
-			float3 tint)
+			in float3 tint)
 		{
 			this.models = models;
 			this.pos = pos;
@@ -92,7 +92,7 @@ namespace OpenRA.Mods.Common.Graphics
 
 		public IRenderable AsDecoration() { return this; }
 
-		public IRenderable WithTint(float3 newTint)
+		public IRenderable WithTint(in float3 newTint)
 		{
 			return new ModelRenderable(
 				models, pos, zOffset, camera, scale,
@@ -195,7 +195,7 @@ namespace OpenRA.Mods.Common.Graphics
 			static readonly uint[] CornerXIndex = new uint[] { 0, 0, 0, 0, 3, 3, 3, 3 };
 			static readonly uint[] CornerYIndex = new uint[] { 1, 1, 4, 4, 1, 1, 4, 4 };
 			static readonly uint[] CornerZIndex = new uint[] { 2, 5, 2, 5, 2, 5, 2, 5 };
-			static void DrawBoundsBox(WorldRenderer wr, float3 pxPos, float[] transform, float[] bounds, float width, Color c)
+			static void DrawBoundsBox(WorldRenderer wr, in float3 pxPos, float[] transform, float[] bounds, float width, Color c)
 			{
 				var cr = Game.Renderer.RgbaColorRenderer;
 				var corners = new float2[8];
diff --git a/OpenRA.Mods.Common/Traits/TerrainLighting.cs b/OpenRA.Mods.Common/Traits/TerrainLighting.cs
index 1d00ea6e2d..4c060097e9 100644
--- a/OpenRA.Mods.Common/Traits/TerrainLighting.cs
+++ b/OpenRA.Mods.Common/Traits/TerrainLighting.cs
@@ -42,7 +42,7 @@ namespace OpenRA.Mods.Common.Traits
 			public readonly float Intensity;
 			public readonly float3 Tint;
 
-			public LightSource(WPos pos, CPos cell, WDist range, float intensity, float3 tint)
+			public LightSource(WPos pos, CPos cell, WDist range, float intensity, in float3 tint)
 			{
 				Pos = pos;
 				Cell = cell;
@@ -81,7 +81,7 @@ namespace OpenRA.Mods.Common.Traits
 			return new Rectangle(c.X - r, c.Y - r, 2 * r, 2 * r);
 		}
 
-		public int AddLightSource(WPos pos, WDist range, float intensity, float3 tint)
+		public int AddLightSource(WPos pos, WDist range, float intensity, in float3 tint)
 		{
 			var token = nextLightSourceToken++;
 			var source = new LightSource(pos, map.CellContaining(pos), range, intensity, tint);
diff --git a/OpenRA.Mods.Common/Traits/World/ShroudRenderer.cs b/OpenRA.Mods.Common/Traits/World/ShroudRenderer.cs
index 21867ac33e..fc5b5f6186 100644
--- a/OpenRA.Mods.Common/Traits/World/ShroudRenderer.cs
+++ b/OpenRA.Mods.Common/Traits/World/ShroudRenderer.cs
@@ -84,7 +84,7 @@ namespace OpenRA.Mods.Common.Traits
 			public readonly float3 ScreenPosition;
 			public readonly byte Variant;
 
-			public TileInfo(float3 screenPosition, byte variant)
+			public TileInfo(in float3 screenPosition, byte variant)
 			{
 				ScreenPosition = screenPosition;
 				Variant = variant;