Reduce allocations in the main game loop.

- Cache the shroud projection even for flat maps to avoid allocating single element arrays.
- Avoid LINQ in shroud and map projection queries to avoid enumerator allocations.
- Avoid LINQ in calculation of sync values.
- Cache enumerables in ProductionQueue.
- Cache delegate in HackyAI.

OpenRA.Game/Map/Map.cs

@@ -260,8 +260,6 @@ namespace OpenRA
 		[FieldLoader.Ignore] public ProjectedCellRegion ProjectedCellBounds;
 		[FieldLoader.Ignore] public CellRegion AllCells;
 
-		readonly Func<PPos, bool> containsTest;
-
 		void AssertExists(string filename)
 		{
 			using (var s = Container.GetContent(filename))
@@ -275,8 +273,6 @@ namespace OpenRA
 		/// </summary>
 		public Map(TileSet tileset, int width, int height)
 		{
-			containsTest = Contains;
-
 			var size = new Size(width, height);
 			var tileShape = Game.ModData.Manifest.TileShape;
 			var tileRef = new TerrainTile(tileset.Templates.First().Key, (byte)0);
@@ -316,8 +312,6 @@ namespace OpenRA
 		/// <summary>Initializes a map loaded from disk.</summary>
 		public Map(string path)
 		{
-			containsTest = Contains;
-
 			Path = path;
 			Container = GlobalFileSystem.OpenPackage(path, null, int.MaxValue);
 
@@ -448,34 +442,40 @@ namespace OpenRA
 
 			initializedCellProjection = true;
 
-			if (MaximumTerrainHeight != 0)
+			cellProjection = new CellLayer<PPos[]>(this);
+			inverseCellProjection = new CellLayer<List<MPos>>(this);
+
+			// Initialize collections
+			foreach (var cell in AllCells)
 			{
-				cellProjection = new CellLayer<PPos[]>(this);
-				inverseCellProjection = new CellLayer<List<MPos>>(this);
-
-				// Initialize collections
-				foreach (var cell in AllCells)
-				{
-					var uv = cell.ToMPos(TileShape);
-					cellProjection[uv] = new PPos[0];
-					inverseCellProjection[uv] = new List<MPos>();
-				}
-
-				// Initialize projections
-				foreach (var cell in AllCells)
-					UpdateProjection(cell);
+				var uv = cell.ToMPos(TileShape);
+				cellProjection[uv] = new PPos[0];
+				inverseCellProjection[uv] = new List<MPos>();
 			}
+
+			// Initialize projections
+			foreach (var cell in AllCells)
+				UpdateProjection(cell);
 		}
 
 		void UpdateProjection(CPos cell)
 		{
+			MPos uv;
+
 			if (MaximumTerrainHeight == 0)
+			{
+				uv = cell.ToMPos(TileShape);
+				cellProjection[cell] = new[] { (PPos)uv };
+				var inverse = inverseCellProjection[uv];
+				inverse.Clear();
+				inverse.Add(uv);
 				return;
+			}
 
 			if (!initializedCellProjection)
 				InitializeCellProjection();
 
-			var uv = cell.ToMPos(TileShape);
+			uv = cell.ToMPos(TileShape);
 
 			// Remove old reverse projection
 			foreach (var puv in cellProjection[uv])
@@ -630,7 +630,8 @@ namespace OpenRA
 				}
 			}
 
-			tiles.CellEntryChanged += UpdateProjection;
+			if (MaximumTerrainHeight > 0)
+				tiles.CellEntryChanged += UpdateProjection;
 
 			return tiles;
 		}
@@ -650,7 +651,8 @@ namespace OpenRA
 				}
 			}
 
-			tiles.CellEntryChanged += UpdateProjection;
+			if (MaximumTerrainHeight > 0)
+				tiles.CellEntryChanged += UpdateProjection;
 
 			return tiles;
 		}
@@ -755,7 +757,15 @@ namespace OpenRA
 			// The first check ensures that the cell is within the valid map region, avoiding
 			// potential crashes in deeper code.  All CellLayers have the same geometry, and
 			// CustomTerrain is convenient (cellProjection may be null and others are Lazy).
-			return CustomTerrain.Contains(uv) && ProjectedCellsCovering(uv).All(containsTest);
+			return CustomTerrain.Contains(uv) && ContainsAllProjectedCellsCovering(uv);
+		}
+
+		bool ContainsAllProjectedCellsCovering(MPos uv)
+		{
+			foreach (var puv in ProjectedCellsCovering(uv))
+				if (!Contains(puv))
+					return false;
+			return true;
 		}
 
 		public bool Contains(PPos puv)
@@ -822,10 +832,6 @@ namespace OpenRA
 		static readonly PPos[] NoProjectedCells = { };
 		public PPos[] ProjectedCellsCovering(MPos uv)
 		{
-			// Shortcut for mods that don't use heightmaps
-			if (MaximumTerrainHeight == 0)
-				return new[] { (PPos)uv };
-
 			if (!initializedCellProjection)
 				InitializeCellProjection();
 
@@ -835,21 +841,17 @@ namespace OpenRA
 			return cellProjection[uv];
 		}
 
-		public MPos[] Unproject(PPos puv)
+		public List<MPos> Unproject(PPos puv)
 		{
 			var uv = (MPos)puv;
 
-			// Shortcut for mods that don't use heightmaps
-			if (MaximumTerrainHeight == 0)
-				return new[] { uv };
-
 			if (!initializedCellProjection)
 				InitializeCellProjection();
 
 			if (!inverseCellProjection.Contains(uv))
-				return new MPos[0];
+				return new List<MPos>();
 
-			return inverseCellProjection[uv].ToArray();
+			return inverseCellProjection[uv];
 		}
 
 		public int FacingBetween(CPos cell, CPos towards, int fallbackfacing)
@@ -966,7 +968,7 @@ namespace OpenRA
 				return (MPos)Clamp((PPos)uv);
 
 			// Already in bounds, so don't need to do anything.
-			if (ProjectedCellsCovering(uv).Any(containsTest))
+			if (ContainsAllProjectedCellsCovering(uv))
 				return uv;
 
 			// Clamping map coordinates is trickier than it might first look!
@@ -1028,7 +1030,7 @@ namespace OpenRA
 
 		public CPos ChooseRandomCell(MersenneTwister rand)
 		{
-			MPos[] cells;
+			List<MPos> cells;
 			do
 			{
 				var u = rand.Next(Bounds.Left, Bounds.Right);
@@ -1093,7 +1095,7 @@ namespace OpenRA
 
 		public CPos ChooseRandomEdgeCell(MersenneTwister rand)
 		{
-			MPos[] cells;
+			List<MPos> cells;
 			do
 			{
 				var isU = rand.Next(2) == 0;

OpenRA.Game/Traits/World/Shroud.cs

@@ -270,7 +270,11 @@ namespace OpenRA.Traits
 			if (!map.Contains(uv))
 				return false;
 
-			return map.ProjectedCellsCovering(uv).Any(isExploredTest);
+			foreach (var puv in map.ProjectedCellsCovering(uv))
+				if (IsExplored(puv))
+					return true;
+
+			return false;
 		}
 
 		public bool IsExplored(PPos puv)
@@ -316,7 +320,11 @@ namespace OpenRA.Traits
 			if (!visibleCount.Contains(uv))
 				return false;
 
-			return map.ProjectedCellsCovering(uv).Any(isVisibleTest);
+			foreach (var puv in map.ProjectedCellsCovering(uv))
+				if (IsVisible(puv))
+					return true;
+
+			return false;
 		}
 
 		// In internal shroud coords

OpenRA.Mods.Common/AI/HackyAI.cs

@@ -189,6 +189,7 @@ namespace OpenRA.Mods.Common.AI
 
 		public Player Player { get; private set; }
 
+		readonly Func<Actor, bool> isEnemyUnit;
 		Dictionary<SupportPowerInstance, int> waitingPowers = new Dictionary<SupportPowerInstance, int>();
 		Dictionary<string, SupportPowerDecision> powerDecisions = new Dictionary<string, SupportPowerDecision>();
 
@@ -229,6 +230,8 @@ namespace OpenRA.Mods.Common.AI
 		{
 			Info = info;
 			World = init.World;
+			isEnemyUnit = unit =>
+				Player.Stances[unit.Owner] == Stance.Enemy && !unit.HasTrait<Husk>() && unit.HasTrait<ITargetable>();
 
 			foreach (var decision in info.PowerDecisions)
 				powerDecisions.Add(decision.OrderName, decision);
@@ -580,20 +583,12 @@ namespace OpenRA.Mods.Common.AI
 
 		internal Actor FindClosestEnemy(WPos pos)
 		{
-			var allEnemyUnits = World.Actors
-				.Where(unit => Player.Stances[unit.Owner] == Stance.Enemy && !unit.HasTrait<Husk>() &&
-					unit.HasTrait<ITargetable>());
-
-			return allEnemyUnits.ClosestTo(pos);
+			return World.Actors.Where(isEnemyUnit).ClosestTo(pos);
 		}
 
 		internal Actor FindClosestEnemy(WPos pos, WDist radius)
 		{
-			var enemyUnits = World.FindActorsInCircle(pos, radius)
-				.Where(unit => Player.Stances[unit.Owner] == Stance.Enemy &&
-					!unit.HasTrait<Husk>() && unit.HasTrait<ITargetable>());
-
-			return enemyUnits.ClosestTo(pos);
+			return World.FindActorsInCircle(pos, radius).Where(isEnemyUnit).ClosestTo(pos);
 		}
 
 		List<Actor> FindEnemyConstructionYards()

OpenRA.Mods.Common/Traits/Buildings/RepairableBuilding.cs

@@ -40,7 +40,17 @@ namespace OpenRA.Mods.Common.Traits
 	public class RepairableBuilding : UpgradableTrait<RepairableBuildingInfo>, ITick
 	{
 		[Sync]
-		public int RepairersHash { get { return Repairers.Aggregate(0, (code, player) => code ^ Sync.HashPlayer(player)); } }
+		public int RepairersHash
+		{
+			get
+			{
+				var hash = 0;
+				foreach (var player in Repairers)
+					hash ^= Sync.HashPlayer(player);
+				return hash;
+			}
+		}
+
 		public readonly List<Player> Repairers = new List<Player>();
 
 		readonly Health health;
@@ -94,7 +104,9 @@ namespace OpenRA.Mods.Common.Traits
 				Repairers.RemoveAll(isNotActiveAlly);
 
 				// If after the previous operation there's no repairers left, stop
-				if (!Repairers.Any()) return;
+				if (Repairers.Count == 0)
+					return;
+
 				var buildingValue = self.GetSellValue();
 
 				// The cost is the same regardless of the amount of people repairing

OpenRA.Mods.Common/Traits/Harvester.cs

@@ -70,6 +70,7 @@ namespace OpenRA.Mods.Common.Traits
 		readonly HarvesterInfo info;
 		readonly Mobile mobile;
 		Dictionary<ResourceTypeInfo, int> contents = new Dictionary<ResourceTypeInfo, int>();
+		bool idleSmart = true;
 
 		[Sync] public Actor OwnerLinkedProc = null;
 		[Sync] public Actor LastLinkedProc = null;
@@ -77,8 +78,17 @@ namespace OpenRA.Mods.Common.Traits
 		[Sync] int currentUnloadTicks;
 		public CPos? LastHarvestedCell = null;
 		public CPos? LastOrderLocation = null;
-		[Sync] public int ContentValue { get { return contents.Sum(c => c.Key.ValuePerUnit * c.Value); } }
-		bool idleSmart = true;
+		[Sync]
+		public int ContentValue
+		{
+			get
+			{
+				var value = 0;
+				foreach (var c in contents)
+					value += c.Key.ValuePerUnit * c.Value;
+				return value;
+			}
+		}
 
 		public Harvester(Actor self, HarvesterInfo info)
 		{

OpenRA.Mods.Common/Traits/Player/MissionObjectives.cs

@@ -58,7 +58,16 @@ namespace OpenRA.Mods.Common.Traits
 		public ReadOnlyList<MissionObjective> Objectives;
 
 		[Sync]
-		public int ObjectivesHash { get { return Objectives.Aggregate(0, (code, objective) => code ^ Sync.Hash(objective.State)); } }
+		public int ObjectivesHash
+		{
+			get
+			{
+				var hash = 0;
+				foreach (var objective in objectives)
+					hash ^= Sync.Hash(objective.State);
+				return hash;
+			}
+		}
 
 		// This property is used as a flag in 'Cooperative' games to mark that the player has completed all his objectives.
 		// The player's WinState is only updated when his allies have all completed their objective as well.

OpenRA.Mods.Common/Traits/Player/ProductionQueue.cs

@@ -68,15 +68,17 @@ namespace OpenRA.Mods.Common.Traits
 		public readonly ProductionQueueInfo Info;
 		readonly Actor self;
 
+		// A list of things we could possibly build
+		readonly Dictionary<ActorInfo, ProductionState> produceable = new Dictionary<ActorInfo, ProductionState>();
+		readonly List<ProductionItem> queue = new List<ProductionItem>();
+		readonly IEnumerable<ActorInfo> allProduceables;
+		readonly IEnumerable<ActorInfo> buildableProduceables;
+
 		// Will change if the owner changes
 		PowerManager playerPower;
 		PlayerResources playerResources;
 		protected DeveloperMode developerMode;
 
-		// A list of things we could possibly build
-		Dictionary<ActorInfo, ProductionState> produceable;
-		List<ProductionItem> queue = new List<ProductionItem>();
-
 		public Actor Actor { get { return self; } }
 
 		[Sync] public int QueueLength { get { return queue.Count; } }
@@ -101,6 +103,8 @@ namespace OpenRA.Mods.Common.Traits
 			Enabled = !info.Factions.Any() || info.Factions.Contains(Faction);
 
 			CacheProduceables(playerActor);
+			allProduceables = produceable.Where(a => a.Value.Buildable || a.Value.Visible).Select(a => a.Key);
+			buildableProduceables = produceable.Where(a => a.Value.Buildable).Select(a => a.Key);
 		}
 
 		void ClearQueue()
@@ -143,7 +147,7 @@ namespace OpenRA.Mods.Common.Traits
 
 		void CacheProduceables(Actor playerActor)
 		{
-			produceable = new Dictionary<ActorInfo, ProductionState>();
+			produceable.Clear();
 			if (!Enabled)
 				return;
 
@@ -200,9 +204,9 @@ namespace OpenRA.Mods.Common.Traits
 		public virtual IEnumerable<ActorInfo> AllItems()
 		{
 			if (self.World.AllowDevCommands && developerMode.AllTech)
-				return produceable.Select(a => a.Key);
+				return produceable.Keys;
 
-			return produceable.Where(a => a.Value.Buildable || a.Value.Visible).Select(a => a.Key);
+			return allProduceables;
 		}
 
 		public virtual IEnumerable<ActorInfo> BuildableItems()
@@ -210,9 +214,9 @@ namespace OpenRA.Mods.Common.Traits
 			if (!Enabled)
 				return Enumerable.Empty<ActorInfo>();
 			if (self.World.AllowDevCommands && developerMode.AllTech)
-				return produceable.Select(a => a.Key);
+				return produceable.Keys;
 
-			return produceable.Where(a => a.Value.Buildable).Select(a => a.Key);
+			return buildableProduceables;
 		}
 
 		public bool CanBuild(ActorInfo actor)