Added MinBy, MaxBy, MinByOrDefault and MaxByOrDefault methods and replaced calls of the style OrderBy[Descending]().First[OrDefault]() which is not as performant.

OpenRA.Editor/Form1.cs

@@ -162,7 +162,7 @@ namespace OpenRA.Editor
 			foreach (var p in palettes) { p.Visible = false; p.SuspendLayout(); }
 
 			var templateOrder = tileset.EditorTemplateOrder ?? new string[] { };
-			foreach (var tc in tileset.Templates.GroupBy(t => t.Value.Category).OrderBy(t => templateOrder.ToList().IndexOf(t.Key)))
+			foreach (var tc in tileset.Templates.GroupBy(t => t.Value.Category).OrderBy(t => Array.IndexOf(templateOrder, t.Key)))
 			{
 				var category = tc.Key ?? "(Uncategorized)";
 				var categoryHeader = new Label

OpenRA.Game/Exts.cs

@@ -131,6 +131,54 @@ namespace OpenRA
 			for (;;) { yield return t; t = f(t); }
 		}
 
+		public static T MinBy<T, U>(this IEnumerable<T> ts, Func<T, U> selector)
+		{
+			return ts.CompareBy(selector, 1, true);
+		}
+
+		public static T MaxBy<T, U>(this IEnumerable<T> ts, Func<T, U> selector)
+		{
+			return ts.CompareBy(selector, -1, true);
+		}
+
+		public static T MinByOrDefault<T, U>(this IEnumerable<T> ts, Func<T, U> selector)
+		{
+			return ts.CompareBy(selector, 1, false);
+		}
+
+		public static T MaxByOrDefault<T, U>(this IEnumerable<T> ts, Func<T, U> selector)
+		{
+			return ts.CompareBy(selector, -1, false);
+		}
+
+		static T CompareBy<T, U>(this IEnumerable<T> ts, Func<T, U> selector, int modifier, bool throws)
+		{
+			var comparer = Comparer<U>.Default;
+			T t;
+			U u;
+			using (var e = ts.GetEnumerator())
+			{
+				if (!e.MoveNext())
+					if (throws)
+						throw new ArgumentException("Collection must not be empty.", "ts");
+					else
+						return default(T);
+				t = e.Current;
+				u = selector(t);
+				while (e.MoveNext())
+				{
+					T nextT = e.Current;
+					U nextU = selector(nextT);
+					if (comparer.Compare(nextU, u) * modifier < 0)
+					{
+						t = nextT;
+						u = nextU;
+					}
+				}
+				return t;
+			}
+		}
+
 		public static int NextPowerOf2(int v)
 		{
 			--v;

OpenRA.Game/FileSystem/GlobalFileSystem.cs

@@ -156,8 +156,7 @@ namespace OpenRA.FileSystem
 			var index = type == PackageHashType.CRC32 ? crcHashIndex : classicHashIndex;
 			var folder = index[PackageEntry.HashFilename(filename, type)]
 				.Where(x => x.Exists(filename))
-				.OrderBy(x => x.Priority)
+				.MinByOrDefault(x => x.Priority);
-				.FirstOrDefault();
 
 			if (folder != null)
 				return folder.GetContent(filename);
@@ -196,8 +195,7 @@ namespace OpenRA.FileSystem
 			{
 				var folder = MountedFolders
 					.Where(x => x.Exists(filename + ext))
-					.OrderByDescending(x => x.Priority)
+					.MaxByOrDefault(x => x.Priority);
-					.FirstOrDefault();
 
 				if (folder != null)
 				{

OpenRA.Game/Orders/UnitOrderGenerator.cs

@@ -21,8 +21,7 @@ namespace OpenRA.Orders
 		{
 			var underCursor = world.ScreenMap.ActorsAt(mi)
 				.Where(a => !world.FogObscures(a) && a.HasTrait<ITargetable>())
-				.OrderByDescending(a => a.Info.SelectionPriority())
+				.WithHighestSelectionPriority();
-				.FirstOrDefault();
 
 			Target target;
 			if (underCursor != null)
@@ -31,8 +30,7 @@ namespace OpenRA.Orders
 			{
 				var frozen = world.ScreenMap.FrozenActorsAt(world.RenderPlayer, mi)
 					.Where(a => a.Info.Traits.Contains<ITargetableInfo>())
-					.OrderByDescending(a => a.Info.SelectionPriority())
+					.WithHighestSelectionPriority();
-					.FirstOrDefault();
 				target = frozen != null ? Target.FromFrozenActor(frozen) : Target.FromCell(xy);
 			}
 
@@ -61,8 +59,7 @@ namespace OpenRA.Orders
 			var useSelect = false;
 			var underCursor = world.ScreenMap.ActorsAt(mi)
 				.Where(a => !world.FogObscures(a) && a.HasTrait<ITargetable>())
-				.OrderByDescending(a => a.Info.SelectionPriority())
+				.WithHighestSelectionPriority();
-				.FirstOrDefault();
 
 			if (underCursor != null && (mi.Modifiers.HasModifier(Modifiers.Shift) || !world.Selection.Actors.Any()))
 			{
@@ -78,8 +75,7 @@ namespace OpenRA.Orders
 			{
 				var frozen = world.ScreenMap.FrozenActorsAt(world.RenderPlayer, mi)
 					.Where(a => a.Info.Traits.Contains<ITargetableInfo>())
-					.OrderByDescending(a => a.Info.SelectionPriority())
+					.WithHighestSelectionPriority();
-					.FirstOrDefault();
 				target = frozen != null ? Target.FromFrozenActor(frozen) : Target.FromCell(xy);
 			}
 
@@ -161,5 +157,15 @@ namespace OpenRA.Orders
 			var selectableInfo = a.Traits.GetOrDefault<SelectableInfo>();
 			return selectableInfo != null ? selectableInfo.Priority : int.MinValue;
 		}
+
+		public static Actor WithHighestSelectionPriority(this IEnumerable<Actor> actors)
+		{
+			return actors.MaxByOrDefault(a => a.Info.SelectionPriority());
+		}
+
+		public static FrozenActor WithHighestSelectionPriority(this IEnumerable<FrozenActor> actors)
+		{
+			return actors.MaxByOrDefault(a => a.Info.SelectionPriority());
+		}
 	}
 }

OpenRA.Game/Server/Server.cs

@@ -535,7 +535,7 @@ namespace OpenRA.Server
 					LobbyInfo.Clients.RemoveAll(c => c.Bot != null && c.BotControllerClientIndex == toDrop.PlayerIndex);
 
 					var nextAdmin = LobbyInfo.Clients.Where(c1 => c1.Bot == null)
-						.OrderBy(c => c.Index).FirstOrDefault();
+						.MinByOrDefault(c => c.Index);
 
 					if (nextAdmin != null)
 					{

OpenRA.Game/Widgets/ViewportControllerWidget.cs

@@ -106,8 +106,7 @@ namespace OpenRA.Widgets
 
 			var underCursor = world.ScreenMap.ActorsAt(worldRenderer.Viewport.ViewToWorldPx(Viewport.LastMousePos))
 				.Where(a => !world.FogObscures(a) && a.HasTrait<IToolTip>())
-				.OrderByDescending(a => a.Info.SelectionPriority())
+				.WithHighestSelectionPriority();
-				.FirstOrDefault();
 
 			if (underCursor != null)
 			{
@@ -118,8 +117,7 @@ namespace OpenRA.Widgets
 
 			var frozen = world.ScreenMap.FrozenActorsAt(world.RenderPlayer, worldRenderer.Viewport.ViewToWorldPx(Viewport.LastMousePos))
 				.Where(a => a.TooltipName != null)
-				.OrderByDescending(a => a.Info.SelectionPriority())
+				.WithHighestSelectionPriority();
-				.FirstOrDefault();
 
 			if (frozen != null)
 			{

OpenRA.Game/Widgets/WorldInteractionControllerWidget.cs

@@ -93,8 +93,7 @@ namespace OpenRA.Widgets
 					if (multiClick)
 					{
 						var unit = World.ScreenMap.ActorsAt(xy)
-							.OrderByDescending(a => a.Info.SelectionPriority())
+							.WithHighestSelectionPriority();
-							.FirstOrDefault();
 
 						var newSelection2 = SelectActorsInBox(World, worldRenderer.Viewport.TopLeft, worldRenderer.Viewport.BottomRight, 
 							a => unit != null && a.Info.Name == unit.Info.Name && a.Owner == unit.Owner);

OpenRA.Game/WorldUtils.cs

@@ -35,13 +35,12 @@ namespace OpenRA
 
 		public static Actor ClosestTo(this IEnumerable<Actor> actors, Actor a)
 		{
-			var pos = a.CenterPosition;
+			return actors.ClosestTo(a.CenterPosition);
-			return actors.OrderBy(b => (b.CenterPosition - pos).LengthSquared).FirstOrDefault();
 		}
 
 		public static Actor ClosestTo(this IEnumerable<Actor> actors, WPos pos)
 		{
-			return actors.OrderBy(a => (a.CenterPosition - pos).LengthSquared).FirstOrDefault();
+			return actors.MinByOrDefault(a => (a.CenterPosition - pos).LengthSquared);
 		}
 
 		public static IEnumerable<Actor> FindActorsInCircle(this World world, WPos origin, WRange r)

OpenRA.Mods.Cnc/Widgets/ProductionPaletteWidget.cs

@@ -213,7 +213,7 @@ namespace OpenRA.Mods.Cnc.Widgets
 			if (CurrentQueue == null)
 				return;
 
-			var buildableItems = CurrentQueue.BuildableItems().OrderBy(a => a.Traits.Get<BuildableInfo>().BuildPaletteOrder);
+			var buildableItems = CurrentQueue.BuildableItems();
 
 			// Background
 			foreach (var rect in icons.Keys)

OpenRA.Mods.RA/AI/HackyAI.cs

@@ -298,7 +298,7 @@ namespace OpenRA.Mods.RA.AI
 				// Try to maintain 20% excess power
 				if (!HasAdequatePower())
 					return buildableThings.Where(a => GetPowerProvidedBy(a) > 0)
-						.OrderByDescending(a => GetPowerProvidedBy(a)).FirstOrDefault();
+						.MaxByOrDefault(a => GetPowerProvidedBy(a));
 
 				if (playerResource.AlertSilo)
 					return GetBuildingInfoByCommonName("Silo", p);
@@ -365,9 +365,13 @@ namespace OpenRA.Mods.RA.AI
 
 				case BuildingType.Refinery:
 					var tilesPos = world.FindTilesInCircle(baseCenter, MaxBaseDistance)
-						.Where(a => resourceTypes.Contains(world.GetTerrainType(new CPos(a.X, a.Y))))
+						.Where(a => resourceTypes.Contains(world.GetTerrainType(new CPos(a.X, a.Y))));
-						.OrderBy(a => (a.CenterPosition - baseCenter.CenterPosition).LengthSquared);
+					if (tilesPos.Any())
-					return tilesPos.Any() ? findPos(tilesPos.First().CenterPosition, baseCenter) : null;
+					{
+						var pos = tilesPos.MinBy(a => (a.CenterPosition - baseCenter.CenterPosition).LengthSquared);
+						return findPos(pos.CenterPosition, baseCenter);
+					}
+					return null;
 
 				case BuildingType.Building:
 					for (var k = 0; k < maxBaseDistance; k++)
@@ -426,8 +430,7 @@ namespace OpenRA.Mods.RA.AI
 
 			var leastLikedEnemies = liveEnemies
 				.GroupBy(e => aggro[e].Aggro)
-				.OrderByDescending(g => g.Key)
+				.MaxByOrDefault(g => g.Key);
-				.FirstOrDefault();
 
 			var enemy = (leastLikedEnemies != null) ?
 				leastLikedEnemies.Random(random) : liveEnemies.FirstOrDefault();
@@ -457,12 +460,9 @@ namespace OpenRA.Mods.RA.AI
 		{
 			var allEnemyUnits = world.Actors
 				.Where(unit => p.Stances[unit.Owner] == Stance.Enemy && !unit.HasTrait<Husk>() &&
-					unit.HasTrait<ITargetable>()).ToList();
+					unit.HasTrait<ITargetable>());
 
-			if (allEnemyUnits.Count > 0)
+			return allEnemyUnits.ClosestTo(pos);
-				return allEnemyUnits.ClosestTo(pos);
-
-			return null;
 		}
 
 		internal Actor FindClosestEnemy(WPos pos, WRange radius)

OpenRA.Mods.RA/Activities/Teleport.cs

@@ -93,7 +93,7 @@ namespace OpenRA.Mods.RA.Activities
 			var restrictTo = maximumDistance == null ? null : self.World.FindTilesInCircle(self.Location, maximumDistance.Value);
 
 			if (maximumDistance != null)
-				destination = restrictTo.OrderBy(x => (x - destination).Length).First();
+				destination = restrictTo.MinBy(x => (x - destination).LengthSquared);
 
 			var pos = self.Trait<IPositionable>();
 			if (pos.CanEnterCell(destination) && self.Owner.Shroud.IsExplored(destination))

OpenRA.Mods.RA/Air/ReturnToBase.cs

@@ -69,8 +69,7 @@ namespace OpenRA.Mods.RA.Air
 			var side = new WVec(-fwd.Y, fwd.X, fwd.Z);
 			var approachDelta = self.CenterPosition - approachStart;
 			var sideTowardBase = new[] { side, -side }
-				.OrderBy(a => WVec.Dot(a, approachDelta))
+				.MinBy(a => WVec.Dot(a, approachDelta));
-				.First();
 
 			// Calculate the tangent line that joins the turning circles at the current and approach positions
 			var cp = self.CenterPosition + turnRadius * sideTowardBase / 1024;

OpenRA.Mods.RA/MPStartLocations.cs

@@ -77,9 +77,7 @@ namespace OpenRA.Mods.RA
 				? world.SharedRandom.Next(available.Count)
 				: available			// pick the most distant spawnpoint from everyone else
 					.Select((k, i) => Pair.New(k, i))
-					.OrderByDescending(a => taken.Sum(t => (t - a.First).LengthSquared))
+					.MaxBy(a => taken.Sum(t => (t - a.First).LengthSquared)).Second;
-					.Select(a => a.Second)
-					.First();
 
 			var sp = available[n];
 			available.RemoveAt(n);

OpenRA.Mods.RA/Minelayer.cs

@@ -134,9 +134,8 @@ namespace OpenRA.Mods.RA
 
 				var underCursor = world.ScreenMap.ActorsAt(mi)
 					.Where(a => !world.FogObscures(a))
-					.OrderByDescending(a => a.Info.Traits.Contains<SelectableInfo>()
+					.MaxByOrDefault(a => a.Info.Traits.Contains<SelectableInfo>()
-						? a.Info.Traits.Get<SelectableInfo>().Priority : int.MinValue)
+						? a.Info.Traits.Get<SelectableInfo>().Priority : int.MinValue);
-					.FirstOrDefault();
 
 				if (mi.Button == Game.mouseButtonPreference.Action && underCursor == null)
 				{

OpenRA.Mods.RA/TeslaZapRenderable.cs

@@ -132,7 +132,7 @@ namespace OpenRA.Mods.RA
 			while ((to - z).X > 5 || (to - z).X < -5 || (to - z).Y > 5 || (to - z).Y < -5)
 			{
 				var step = steps.Where(t => (to - (z + new float2(t[0], t[1]))).LengthSquared < (to - z).LengthSquared)
-					.OrderBy(t => Math.Abs(float2.Dot(z + new float2(t[0], t[1]), q) + c)).First();
+					.MinBy(t => Math.Abs(float2.Dot(z + new float2(t[0], t[1]), q) + c));
 
 				var pos = wr.Position((z + new float2(step[2], step[3])).ToInt2());
 				rs.Add(new SpriteRenderable(s.GetSprite(step[4]), pos, WVec.Zero, 0, pal, 1f, true));

OpenRA.Utility/Command.cs

@@ -222,8 +222,7 @@ namespace OpenRA.Utility
 				if (!remap.ContainsKey(i))
 					remap[i] = fullIndexRange
 						.Where(a => !remap.ContainsValue(a))
-						.OrderBy(a => ColorDistance(destPalette.Values[a], srcPalette.Values[i]))
+						.MinBy(a => ColorDistance(destPalette.Values[a], srcPalette.Values[i]));
-						.First();
 
 			var srcImage = ShpReader.Load(args[3]);