diff --git a/OpenRA.Game/Graphics/WorldRenderer.cs b/OpenRA.Game/Graphics/WorldRenderer.cs
index d39113a935..df7c68abc8 100644
--- a/OpenRA.Game/Graphics/WorldRenderer.cs
+++ b/OpenRA.Game/Graphics/WorldRenderer.cs
@@ -185,8 +185,7 @@ namespace OpenRA.Graphics
 
 			if (World.Type == WorldType.Regular && Game.Settings.Game.AlwaysShowStatusBars)
 			{
-				foreach (var g in World.Actors.Where(a => !a.Disposed
-					&& a.Info.HasTraitInfo<SelectableInfo>()
+				foreach (var g in World.ActorsHavingTrait<Selectable>().Where(a => !a.Disposed
 					&& !World.FogObscures(a)
 					&& !World.Selection.Actors.Contains(a)))
 
diff --git a/OpenRA.Game/TraitDictionary.cs b/OpenRA.Game/TraitDictionary.cs
index 3d6a9dbe30..b8fa17ef1b 100644
--- a/OpenRA.Game/TraitDictionary.cs
+++ b/OpenRA.Game/TraitDictionary.cs
@@ -107,6 +107,16 @@ namespace OpenRA
 			return InnerGet<T>().All();
 		}
 
+		public IEnumerable<Actor> ActorsHavingTrait<T>()
+		{
+			return InnerGet<T>().Actors();
+		}
+
+		public IEnumerable<Actor> ActorsHavingTrait<T>(Func<T, bool> predicate)
+		{
+			return InnerGet<T>().Actors(predicate);
+		}
+
 		public void RemoveActor(Actor a)
 		{
 			foreach (var t in traits)
@@ -196,6 +206,33 @@ namespace OpenRA
 				return new AllEnumerable(this);
 			}
 
+			public IEnumerable<Actor> Actors()
+			{
+				++Queries;
+				Actor last = null;
+				for (var i = 0; i < actors.Count; i++)
+				{
+					if (actors[i] == last)
+						continue;
+					yield return actors[i];
+					last = actors[i];
+				}
+			}
+
+			public IEnumerable<Actor> Actors(Func<T, bool> predicate)
+			{
+				++Queries;
+				Actor last = null;
+
+				for (var i = 0; i < actors.Count; i++)
+				{
+					if (actors[i] == last || !predicate(traits[i]))
+						continue;
+					yield return actors[i];
+					last = actors[i];
+				}
+			}
+
 			class AllEnumerable : IEnumerable<TraitPair<T>>
 			{
 				readonly TraitContainer<T> container;
diff --git a/OpenRA.Game/World.cs b/OpenRA.Game/World.cs
index e848a8db52..f6f03ced2a 100644
--- a/OpenRA.Game/World.cs
+++ b/OpenRA.Game/World.cs
@@ -351,6 +351,16 @@ namespace OpenRA
 			return TraitDict.ActorsWithTrait<T>();
 		}
 
+		public IEnumerable<Actor> ActorsHavingTrait<T>()
+		{
+			return TraitDict.ActorsHavingTrait<T>();
+		}
+
+		public IEnumerable<Actor> ActorsHavingTrait<T>(Func<T, bool> predicate)
+		{
+			return TraitDict.ActorsHavingTrait<T>(predicate);
+		}
+
 		public void OnPlayerWinStateChanged(Player player)
 		{
 			var pi = gameInfo.GetPlayer(player);
diff --git a/OpenRA.Mods.Common/AI/BaseBuilder.cs b/OpenRA.Mods.Common/AI/BaseBuilder.cs
index 30e350ab38..babe172c87 100644
--- a/OpenRA.Mods.Common/AI/BaseBuilder.cs
+++ b/OpenRA.Mods.Common/AI/BaseBuilder.cs
@@ -59,13 +59,8 @@ namespace OpenRA.Mods.Common.AI
 			// If failed to place something N consecutive times, wait M ticks until resuming building production
 			if (failCount >= ai.Info.MaximumFailedPlacementAttempts && --failRetryTicks <= 0)
 			{
-				var currentBuildings = world.ActorsWithTrait<Building>()
-					.Where(a => a.Actor.Owner == player)
-					.Count();
-
-				var baseProviders = world.ActorsWithTrait<BaseProvider>()
-					.Where(a => a.Actor.Owner == player)
-					.Count();
+				var currentBuildings = world.ActorsHavingTrait<Building>().Count(a => a.Owner == player);
+				var baseProviders = world.ActorsHavingTrait<BaseProvider>().Count(a => a.Owner == player);
 
 				// Only bother resetting failCount if either a) the number of buildings has decreased since last failure M ticks ago,
 				// or b) number of BaseProviders (construction yard or similar) has increased since then.
@@ -89,9 +84,7 @@ namespace OpenRA.Mods.Common.AI
 
 			if (waterState == Water.NotEnoughWater && --checkForBasesTicks <= 0)
 			{
-				var currentBases = world.ActorsWithTrait<BaseProvider>()
-					.Where(a => a.Actor.Owner == player)
-					.Count();
+				var currentBases = world.ActorsHavingTrait<BaseProvider>().Count(a => a.Owner == player);
 
 				if (currentBases > cachedBases)
 				{
@@ -104,10 +97,7 @@ namespace OpenRA.Mods.Common.AI
 			if (--waitTicks > 0)
 				return;
 
-			playerBuildings = world.ActorsWithTrait<Building>()
-				.Where(a => a.Actor.Owner == player)
-				.Select(a => a.Actor)
-				.ToArray();
+			playerBuildings = world.ActorsHavingTrait<Building>().Where(a => a.Owner == player).ToArray();
 
 			var active = false;
 			foreach (var queue in ai.FindQueues(category))
@@ -158,13 +148,8 @@ namespace OpenRA.Mods.Common.AI
 					// If we just reached the maximum fail count, cache the number of current structures
 					if (failCount == ai.Info.MaximumFailedPlacementAttempts)
 					{
-						cachedBuildings = world.ActorsWithTrait<Building>()
-							.Where(a => a.Actor.Owner == player)
-							.Count();
-
-						cachedBases = world.ActorsWithTrait<BaseProvider>()
-							.Where(a => a.Actor.Owner == player)
-							.Count();
+						cachedBuildings = world.ActorsHavingTrait<Building>().Count(a => a.Owner == player);
+						cachedBases = world.ActorsHavingTrait<BaseProvider>().Count(a => a.Owner == player);
 					}
 				}
 				else
diff --git a/OpenRA.Mods.Common/AI/HackyAI.cs b/OpenRA.Mods.Common/AI/HackyAI.cs
index 5a7ace582e..02f85a49a5 100644
--- a/OpenRA.Mods.Common/AI/HackyAI.cs
+++ b/OpenRA.Mods.Common/AI/HackyAI.cs
@@ -171,10 +171,8 @@ namespace OpenRA.Mods.Common.AI
 
 		public CPos GetRandomBaseCenter()
 		{
-			var randomBaseBuilding = World.Actors.Where(
-				a => a.Owner == Player
-					&& a.Info.HasTraitInfo<BaseBuildingInfo>()
-					&& !a.Info.HasTraitInfo<MobileInfo>())
+			var randomBaseBuilding = World.ActorsHavingTrait<BaseBuilding>()
+				.Where(a => a.Owner == Player && !a.Info.HasTraitInfo<MobileInfo>())
 				.RandomOrDefault(Random);
 
 			return randomBaseBuilding != null ? randomBaseBuilding.Location : initialBaseCenter;
@@ -288,10 +286,8 @@ namespace OpenRA.Mods.Common.AI
 		// TODO: Possibly give this a more generic name when terrain type is unhardcoded
 		public bool EnoughWaterToBuildNaval()
 		{
-			var baseProviders = World.Actors.Where(
-				a => a.Owner == Player
-					&& a.Info.HasTraitInfo<BaseProviderInfo>()
-					&& !a.Info.HasTraitInfo<MobileInfo>());
+			var baseProviders = World.ActorsHavingTrait<BaseProvider>()
+				.Where(a => a.Owner == Player && !a.Info.HasTraitInfo<MobileInfo>());
 
 			foreach (var b in baseProviders)
 			{
@@ -315,10 +311,8 @@ namespace OpenRA.Mods.Common.AI
 		// Check whether we have at least one building providing buildable area close enough to water to build naval structures
 		public bool CloseEnoughToWater()
 		{
-			var areaProviders = World.Actors.Where(
-				a => a.Owner == Player
-					&& a.Info.HasTraitInfo<GivesBuildableAreaInfo>()
-					&& !a.Info.HasTraitInfo<MobileInfo>());
+			var areaProviders = World.ActorsHavingTrait<GivesBuildableArea>()
+				.Where(a => a.Owner == Player && !a.Info.HasTraitInfo<MobileInfo>());
 
 			foreach (var a in areaProviders)
 			{
@@ -361,9 +355,9 @@ namespace OpenRA.Mods.Common.AI
 				return null;
 
 			var myUnits = Player.World
-				.ActorsWithTrait<IPositionable>()
-				.Where(a => a.Actor.Owner == Player)
-				.Select(a => a.Actor.Info.Name).ToList();
+				.ActorsHavingTrait<IPositionable>()
+				.Where(a => a.Owner == Player)
+				.Select(a => a.Info.Name).ToList();
 
 			foreach (var unit in Info.UnitsToBuild.Shuffle(Random))
 				if (buildableThings.Any(b => b.Name == unit.Key))
@@ -376,14 +370,12 @@ namespace OpenRA.Mods.Common.AI
 
 		int CountBuilding(string frac, Player owner)
 		{
-			return World.ActorsWithTrait<Building>()
-				.Count(a => a.Actor.Owner == owner && a.Actor.Info.Name == frac);
+			return World.ActorsHavingTrait<Building>().Count(a => a.Owner == owner && a.Info.Name == frac);
 		}
 
 		int CountUnits(string unit, Player owner)
 		{
-			return World.ActorsWithTrait<IPositionable>()
-				.Count(a => a.Actor.Owner == owner && a.Actor.Info.Name == unit);
+			return World.ActorsHavingTrait<IPositionable>().Count(a => a.Owner == owner && a.Info.Name == unit);
 		}
 
 		int? CountBuildingByCommonName(string commonName, Player owner)
@@ -391,8 +383,8 @@ namespace OpenRA.Mods.Common.AI
 			if (!Info.BuildingCommonNames.ContainsKey(commonName))
 				return null;
 
-			return World.ActorsWithTrait<Building>()
-				.Count(a => a.Actor.Owner == owner && Info.BuildingCommonNames[commonName].Contains(a.Actor.Info.Name));
+			return World.ActorsHavingTrait<Building>()
+				.Count(a => a.Owner == owner && Info.BuildingCommonNames[commonName].Contains(a.Info.Name));
 		}
 
 		public ActorInfo GetBuildingInfoByCommonName(string commonName, Player owner)
@@ -498,7 +490,7 @@ namespace OpenRA.Mods.Common.AI
 				case BuildingType.Defense:
 
 					// Build near the closest enemy structure
-					var closestEnemy = World.Actors.Where(a => !a.Disposed && a.Info.HasTraitInfo<BuildingInfo>() && Player.Stances[a.Owner] == Stance.Enemy)
+					var closestEnemy = World.ActorsHavingTrait<Building>().Where(a => !a.Disposed && Player.Stances[a.Owner] == Stance.Enemy)
 						.ClosestTo(World.Map.CenterOfCell(defenseCenter));
 
 					var targetCell = closestEnemy != null ? closestEnemy.Location : baseCenter;
@@ -573,8 +565,8 @@ namespace OpenRA.Mods.Common.AI
 				leastLikedEnemies.Random(Random) : liveEnemies.FirstOrDefault();
 
 			// Pick something worth attacking owned by that player
-			var target = World.Actors
-				.Where(a => a.Owner == enemy && a.OccupiesSpace != null)
+			var target = World.ActorsHavingTrait<IOccupySpace>()
+				.Where(a => a.Owner == enemy)
 				.ClosestTo(World.Map.CenterOfCell(GetRandomBaseCenter()));
 
 			if (target == null)
@@ -605,8 +597,8 @@ namespace OpenRA.Mods.Common.AI
 
 		List<Actor> FindEnemyConstructionYards()
 		{
-			return World.Actors.Where(a => Player.Stances[a.Owner] == Stance.Enemy && !a.IsDead
-				&& a.Info.HasTraitInfo<BaseBuildingInfo>() && !a.Info.HasTraitInfo<MobileInfo>()).ToList();
+			return World.ActorsHavingTrait<BaseBuilding>()
+				.Where(a => Player.Stances[a.Owner] == Stance.Enemy && !a.IsDead && !a.Info.HasTraitInfo<MobileInfo>()).ToList();
 		}
 
 		void CleanSquads()
@@ -716,10 +708,8 @@ namespace OpenRA.Mods.Common.AI
 
 		void FindNewUnits(Actor self)
 		{
-			var newUnits = self.World.ActorsWithTrait<IPositionable>()
-				.Where(a => a.Actor.Owner == Player && !a.Actor.Info.HasTraitInfo<BaseBuildingInfo>()
-					&& !activeUnits.Contains(a.Actor))
-				.Select(a => a.Actor);
+			var newUnits = self.World.ActorsHavingTrait<IPositionable>()
+				.Where(a => a.Owner == Player && !a.Info.HasTraitInfo<BaseBuildingInfo>() && !activeUnits.Contains(a));
 
 			foreach (var a in newUnits)
 			{
@@ -843,8 +833,7 @@ namespace OpenRA.Mods.Common.AI
 		void InitializeBase(Actor self)
 		{
 			// Find and deploy our mcv
-			var mcv = self.World.Actors
-				.FirstOrDefault(a => a.Owner == Player && a.Info.HasTraitInfo<BaseBuildingInfo>());
+			var mcv = self.World.ActorsHavingTrait<BaseBuilding>().FirstOrDefault(a => a.Owner == Player);
 
 			if (mcv != null)
 			{
@@ -865,8 +854,8 @@ namespace OpenRA.Mods.Common.AI
 		void FindAndDeployBackupMcv(Actor self)
 		{
 			// HACK: This needs to query against MCVs directly
-			var mcvs = self.World.Actors
-				.Where(a => a.Owner == Player && a.Info.HasTraitInfo<BaseBuildingInfo>() && a.Info.HasTraitInfo<MobileInfo>());
+			var mcvs = self.World.ActorsHavingTrait<BaseBuilding>()
+				.Where(a => a.Owner == Player && a.Info.HasTraitInfo<MobileInfo>());
 
 			foreach (var mcv in mcvs)
 			{
@@ -1023,8 +1012,8 @@ namespace OpenRA.Mods.Common.AI
 				return;
 
 			// No construction yards - Build a new MCV
-			if (!HasAdequateFact() && !self.World.Actors.Any(a =>
-					a.Owner == Player && a.Info.HasTraitInfo<BaseBuildingInfo>() && a.Info.HasTraitInfo<MobileInfo>()))
+			if (!HasAdequateFact() && !self.World.ActorsHavingTrait<BaseBuilding>()
+					.Any(a => a.Owner == Player && a.Info.HasTraitInfo<MobileInfo>()))
 				BuildUnit("Vehicle", GetUnitInfoByCommonName("Mcv", Player).Name);
 
 			foreach (var q in Info.UnitQueues)
diff --git a/OpenRA.Mods.Common/AI/States/StateBase.cs b/OpenRA.Mods.Common/AI/States/StateBase.cs
index d8c5143ec1..b63d0d0cde 100644
--- a/OpenRA.Mods.Common/AI/States/StateBase.cs
+++ b/OpenRA.Mods.Common/AI/States/StateBase.cs
@@ -31,8 +31,8 @@ namespace OpenRA.Mods.Common.AI
 		protected static CPos RandomBuildingLocation(Squad squad)
 		{
 			var location = squad.Bot.GetRandomBaseCenter();
-			var buildings = squad.World.ActorsWithTrait<Building>()
-				.Where(a => a.Actor.Owner == squad.Bot.Player).Select(a => a.Actor).ToList();
+			var buildings = squad.World.ActorsHavingTrait<Building>()
+				.Where(a => a.Owner == squad.Bot.Player).ToList();
 			if (buildings.Count > 0)
 				location = buildings.Random(squad.Random).Location;
 			return location;
diff --git a/OpenRA.Mods.Common/Activities/Air/HeliReturnToBase.cs b/OpenRA.Mods.Common/Activities/Air/HeliReturnToBase.cs
index 7c9ee1a58a..be38ab6235 100644
--- a/OpenRA.Mods.Common/Activities/Air/HeliReturnToBase.cs
+++ b/OpenRA.Mods.Common/Activities/Air/HeliReturnToBase.cs
@@ -42,9 +42,8 @@ namespace OpenRA.Mods.Common.Activities
 			if (dest == null)
 			{
 				var rearmBuildings = heli.Info.RearmBuildings;
-				var nearestHpad = self.World.ActorsWithTrait<Reservable>()
-									.Where(a => a.Actor.Owner == self.Owner && rearmBuildings.Contains(a.Actor.Info.Name))
-									.Select(a => a.Actor)
+				var nearestHpad = self.World.ActorsHavingTrait<Reservable>()
+									.Where(a => a.Owner == self.Owner && rearmBuildings.Contains(a.Info.Name))
 									.ClosestTo(self);
 
 				if (nearestHpad == null)
diff --git a/OpenRA.Mods.Common/Activities/Air/ReturnToBase.cs b/OpenRA.Mods.Common/Activities/Air/ReturnToBase.cs
index ff485f4549..6a9bb29656 100644
--- a/OpenRA.Mods.Common/Activities/Air/ReturnToBase.cs
+++ b/OpenRA.Mods.Common/Activities/Air/ReturnToBase.cs
@@ -34,11 +34,10 @@ namespace OpenRA.Mods.Common.Activities
 		public static Actor ChooseAirfield(Actor self, bool unreservedOnly)
 		{
 			var rearmBuildings = self.Info.TraitInfo<AircraftInfo>().RearmBuildings;
-			return self.World.ActorsWithTrait<Reservable>()
-				.Where(a => a.Actor.Owner == self.Owner)
-				.Where(a => rearmBuildings.Contains(a.Actor.Info.Name)
-					&& (!unreservedOnly || !Reservable.IsReserved(a.Actor)))
-				.Select(a => a.Actor)
+			return self.World.ActorsHavingTrait<Reservable>()
+				.Where(a => a.Owner == self.Owner
+					&& rearmBuildings.Contains(a.Info.Name)
+					&& (!unreservedOnly || !Reservable.IsReserved(a)))
 				.ClosestTo(self);
 		}
 
diff --git a/OpenRA.Mods.Common/Activities/Hunt.cs b/OpenRA.Mods.Common/Activities/Hunt.cs
index 99859b53f9..d101a3ede1 100644
--- a/OpenRA.Mods.Common/Activities/Hunt.cs
+++ b/OpenRA.Mods.Common/Activities/Hunt.cs
@@ -23,7 +23,7 @@ namespace OpenRA.Mods.Common.Activities
 		public Hunt(Actor self)
 		{
 			var attack = self.Trait<AttackBase>();
-			targets = self.World.ActorsWithTrait<Huntable>().Select(p => p.Actor).Where(
+			targets = self.World.ActorsHavingTrait<Huntable>().Where(
 				a => self != a && !a.IsDead && a.IsInWorld && a.AppearsHostileTo(self)
 				&& IsTargetable(a, self) && attack.HasAnyValidWeapons(Target.FromActor(a)));
 		}
diff --git a/OpenRA.Mods.Common/PlayerExtensions.cs b/OpenRA.Mods.Common/PlayerExtensions.cs
index 62299806c1..c17495f13c 100644
--- a/OpenRA.Mods.Common/PlayerExtensions.cs
+++ b/OpenRA.Mods.Common/PlayerExtensions.cs
@@ -17,11 +17,9 @@ namespace OpenRA.Mods.Common
 	{
 		public static bool HasNoRequiredUnits(this Player player)
 		{
-			return !player.World.ActorsWithTrait<MustBeDestroyed>().Any(p =>
-			{
-				return p.Actor.Owner == player &&
-					(player.World.LobbyInfo.GlobalSettings.ShortGame ? p.Trait.Info.RequiredForShortGame : p.Actor.IsInWorld);
-			});
+			if (player.World.LobbyInfo.GlobalSettings.ShortGame)
+				return !player.World.ActorsHavingTrait<MustBeDestroyed>(t => t.Info.RequiredForShortGame).Any(a => a.Owner == player);
+			return !player.World.ActorsHavingTrait<MustBeDestroyed>().Any(a => a.Owner == player && a.IsInWorld);
 		}
 	}
 }
\ No newline at end of file
diff --git a/OpenRA.Mods.Common/Scripting/Properties/PlayerProperties.cs b/OpenRA.Mods.Common/Scripting/Properties/PlayerProperties.cs
index f723aa0b6c..190b5b7e87 100644
--- a/OpenRA.Mods.Common/Scripting/Properties/PlayerProperties.cs
+++ b/OpenRA.Mods.Common/Scripting/Properties/PlayerProperties.cs
@@ -55,7 +55,7 @@ namespace OpenRA.Mods.Common.Scripting
 		[Desc("Returns an array of actors representing all ground attack units of this player.")]
 		public Actor[] GetGroundAttackers()
 		{
-			return Player.World.ActorsWithTrait<AttackBase>().Select(a => a.Actor)
+			return Player.World.ActorsHavingTrait<AttackBase>()
 				.Where(a => a.Owner == Player && !a.IsDead && a.IsInWorld && a.Info.HasTraitInfo<MobileInfo>())
 				.ToArray();
 		}
diff --git a/OpenRA.Mods.Common/Traits/Air/ReturnOnIdle.cs b/OpenRA.Mods.Common/Traits/Air/ReturnOnIdle.cs
index 64c8de885b..3c21d70ad3 100644
--- a/OpenRA.Mods.Common/Traits/Air/ReturnOnIdle.cs
+++ b/OpenRA.Mods.Common/Traits/Air/ReturnOnIdle.cs
@@ -36,14 +36,12 @@ namespace OpenRA.Mods.Common.Traits
 				// nowhere to land, pick something friendly and circle over it.
 
 				// i'd prefer something we own
-				var someBuilding = self.World.ActorsWithTrait<Building>()
-					.Select(a => a.Actor)
+				var someBuilding = self.World.ActorsHavingTrait<Building>()
 					.FirstOrDefault(a => a.Owner == self.Owner);
 
 				// failing that, something unlikely to shoot at us
 				if (someBuilding == null)
-					someBuilding = self.World.ActorsWithTrait<Building>()
-						.Select(a => a.Actor)
+					someBuilding = self.World.ActorsHavingTrait<Building>()
 						.FirstOrDefault(a => self.Owner.Stances[a.Owner] == Stance.Ally);
 
 				if (someBuilding == null)
diff --git a/OpenRA.Mods.Common/Traits/Buildings/BuildingUtils.cs b/OpenRA.Mods.Common/Traits/Buildings/BuildingUtils.cs
index 2cb56e7ffa..80fd1af5c9 100644
--- a/OpenRA.Mods.Common/Traits/Buildings/BuildingUtils.cs
+++ b/OpenRA.Mods.Common/Traits/Buildings/BuildingUtils.cs
@@ -72,10 +72,9 @@ namespace OpenRA.Mods.Common.Traits
 						continue; // Cell is empty; continue search
 
 					// Cell contains an actor. Is it the type we want?
-					if (world.ActorsWithTrait<LineBuildNode>().Any(a =>
-					(a.Actor.Location == cell &&
-						a.Actor.Info.TraitInfo<LineBuildNodeInfo>()
-						.Types.Overlaps(lbi.NodeTypes))))
+					if (world.ActorsHavingTrait<LineBuildNode>()
+						.Any(a => a.Location == cell
+							&& a.Info.TraitInfo<LineBuildNodeInfo>().Types.Overlaps(lbi.NodeTypes)))
 						dirs[d] = i; // Cell contains actor of correct type
 					else
 						dirs[d] = -1; // Cell is blocked by another actor type
diff --git a/OpenRA.Mods.Common/Traits/Crates/GiveMcvCrateAction.cs b/OpenRA.Mods.Common/Traits/Crates/GiveMcvCrateAction.cs
index fc36ddacb2..aa5b399de8 100644
--- a/OpenRA.Mods.Common/Traits/Crates/GiveMcvCrateAction.cs
+++ b/OpenRA.Mods.Common/Traits/Crates/GiveMcvCrateAction.cs
@@ -36,8 +36,8 @@ namespace OpenRA.Mods.Common.Traits
 			if (!CanGiveTo(collector))
 				return 0;
 
-			var hasBase = collector.World.ActorsWithTrait<BaseBuilding>()
-				.Any(a => a.Actor.Owner == collector.Owner);
+			var hasBase = collector.World.ActorsHavingTrait<BaseBuilding>()
+				.Any(a => a.Owner == collector.Owner);
 
 			return hasBase ? info.SelectionShares : info.NoBaseSelectionShares;
 		}
diff --git a/OpenRA.Mods.Common/Traits/Harvester.cs b/OpenRA.Mods.Common/Traits/Harvester.cs
index 72b7685982..6e6f407b6d 100644
--- a/OpenRA.Mods.Common/Traits/Harvester.cs
+++ b/OpenRA.Mods.Common/Traits/Harvester.cs
@@ -114,9 +114,8 @@ namespace OpenRA.Mods.Common.Traits
 			if (proc == null) return;
 			if (proc.Disposed) return;
 
-			var linkedHarvs = proc.World.ActorsWithTrait<Harvester>()
-				.Where(a => a.Trait.LinkedProc == proc)
-				.Select(a => Target.FromActor(a.Actor))
+			var linkedHarvs = proc.World.ActorsHavingTrait<Harvester>(h => h.LinkedProc == proc)
+				.Select(a => Target.FromActor(a))
 				.ToList();
 
 			proc.SetTargetLines(linkedHarvs, Color.Gold);
@@ -163,7 +162,7 @@ namespace OpenRA.Mods.Common.Traits
 				.Select(r => new {
 					Location = r.Actor.Location + r.Trait.DeliveryOffset,
 					Actor = r.Actor,
-					Occupancy = self.World.ActorsWithTrait<Harvester>().Count(a => a.Trait.LinkedProc == r.Actor) })
+					Occupancy = self.World.ActorsHavingTrait<Harvester>(h => h.LinkedProc == r.Actor).Count() })
 				.ToDictionary(r => r.Location);
 
 			// Start a search from each refinery's delivery location:
diff --git a/OpenRA.Mods.Common/Traits/Player/ClassicProductionQueue.cs b/OpenRA.Mods.Common/Traits/Player/ClassicProductionQueue.cs
index 23b4c88073..15655c5248 100644
--- a/OpenRA.Mods.Common/Traits/Player/ClassicProductionQueue.cs
+++ b/OpenRA.Mods.Common/Traits/Player/ClassicProductionQueue.cs
@@ -133,10 +133,10 @@ namespace OpenRA.Mods.Common.Traits
 			{
 				var type = bi.BuildAtProductionType ?? info.Type;
 
-				var selfsameBuildingsCount = self.World.ActorsWithTrait<Production>()
+				var selfsameProductionsCount = self.World.ActorsWithTrait<Production>()
 					.Count(p => p.Actor.Owner == self.Owner && p.Trait.Info.Produces.Contains(type));
 
-				var speedModifier = selfsameBuildingsCount.Clamp(1, info.BuildTimeSpeedReduction.Length) - 1;
+				var speedModifier = selfsameProductionsCount.Clamp(1, info.BuildTimeSpeedReduction.Length) - 1;
 				time = (time * info.BuildTimeSpeedReduction[speedModifier]) / 100;
 			}
 
diff --git a/OpenRA.Mods.Common/Traits/Player/ProductionQueue.cs b/OpenRA.Mods.Common/Traits/Player/ProductionQueue.cs
index 9687a6fb8b..54926d79ca 100644
--- a/OpenRA.Mods.Common/Traits/Player/ProductionQueue.cs
+++ b/OpenRA.Mods.Common/Traits/Player/ProductionQueue.cs
@@ -266,7 +266,7 @@ namespace OpenRA.Mods.Common.Traits
 						if (!developerMode.AllTech && bi.BuildLimit > 0)
 						{
 							var inQueue = queue.Count(pi => pi.Item == order.TargetString);
-							var owned = self.Owner.World.ActorsWithTrait<Buildable>().Count(a => a.Actor.Info.Name == order.TargetString && a.Actor.Owner == self.Owner);
+							var owned = self.Owner.World.ActorsHavingTrait<Buildable>().Count(a => a.Info.Name == order.TargetString && a.Owner == self.Owner);
 							fromLimit = bi.BuildLimit - (inQueue + owned);
 
 							if (fromLimit <= 0)
diff --git a/OpenRA.Mods.Common/Traits/Player/StrategicVictoryConditions.cs b/OpenRA.Mods.Common/Traits/Player/StrategicVictoryConditions.cs
index ffd123d7f8..45305c9908 100644
--- a/OpenRA.Mods.Common/Traits/Player/StrategicVictoryConditions.cs
+++ b/OpenRA.Mods.Common/Traits/Player/StrategicVictoryConditions.cs
@@ -56,13 +56,13 @@ namespace OpenRA.Mods.Common.Traits
 			mo = self.Trait<MissionObjectives>();
 		}
 
-		public IEnumerable<TraitPair<StrategicPoint>> AllPoints
+		public IEnumerable<Actor> AllPoints
 		{
-			get { return player.World.ActorsWithTrait<StrategicPoint>(); }
+			get { return player.World.ActorsHavingTrait<StrategicPoint>(); }
 		}
 
 		public int Total { get { return AllPoints.Count(); } }
-		int Owned { get { return AllPoints.Count(a => WorldUtils.AreMutualAllies(player, a.Actor.Owner)); } }
+		int Owned { get { return AllPoints.Count(a => WorldUtils.AreMutualAllies(player, a.Owner)); } }
 
 		public bool Holding { get { return Owned >= info.RatioRequired * Total; } }
 
diff --git a/OpenRA.Mods.Common/Traits/Power/Player/PowerManager.cs b/OpenRA.Mods.Common/Traits/Power/Player/PowerManager.cs
index b4d4e7fb51..3bac6cf4bc 100644
--- a/OpenRA.Mods.Common/Traits/Power/Player/PowerManager.cs
+++ b/OpenRA.Mods.Common/Traits/Power/Player/PowerManager.cs
@@ -138,8 +138,7 @@ namespace OpenRA.Mods.Common.Traits
 
 		void UpdatePowerOutageActors()
 		{
-			var actors = self.World.ActorsWithTrait<AffectedByPowerOutage>()
-				.Select(tp => tp.Actor)
+			var actors = self.World.ActorsHavingTrait<AffectedByPowerOutage>()
 				.Where(a => !a.IsDead && a.IsInWorld && a.Owner == self.Owner);
 
 			foreach (var a in actors)
diff --git a/OpenRA.Mods.Common/Widgets/Logic/Ingame/IngameRadarDisplayLogic.cs b/OpenRA.Mods.Common/Widgets/Logic/Ingame/IngameRadarDisplayLogic.cs
index 20d89addac..f402e0d885 100644
--- a/OpenRA.Mods.Common/Widgets/Logic/Ingame/IngameRadarDisplayLogic.cs
+++ b/OpenRA.Mods.Common/Widgets/Logic/Ingame/IngameRadarDisplayLogic.cs
@@ -31,8 +31,8 @@ namespace OpenRA.Mods.Common.Widgets.Logic
 			var ticker = widget.Get<LogicTickerWidget>("RADAR_TICKER");
 			ticker.OnTick = () =>
 			{
-				radarEnabled = devMode.DisableShroud || world.ActorsWithTrait<ProvidesRadar>()
-					.Any(a => a.Actor.Owner == world.LocalPlayer && a.Trait.IsActive);
+				radarEnabled = devMode.DisableShroud || world.ActorsHavingTrait<ProvidesRadar>(r => r.IsActive)
+					.Any(a => a.Owner == world.LocalPlayer);
 
 				if (radarEnabled != cachedRadarEnabled)
 					Game.Sound.PlayNotification(world.Map.Rules, null, "Sounds", radarEnabled ? "RadarUp" : "RadarDown", null);
diff --git a/OpenRA.Mods.Common/Widgets/Logic/Ingame/ObserverStatsLogic.cs b/OpenRA.Mods.Common/Widgets/Logic/Ingame/ObserverStatsLogic.cs
index 9b7f6e02f8..b0996e4f3f 100644
--- a/OpenRA.Mods.Common/Widgets/Logic/Ingame/ObserverStatsLogic.cs
+++ b/OpenRA.Mods.Common/Widgets/Logic/Ingame/ObserverStatsLogic.cs
@@ -240,12 +240,12 @@ namespace OpenRA.Mods.Common.Widgets.Logic
 			template.Get<LabelWidget>("SPENT").GetText = () => "$" + res.Spent;
 
 			var assets = template.Get<LabelWidget>("ASSETS");
-			assets.GetText = () => "$" + world.Actors
-				.Where(a => a.Owner == player && !a.IsDead && a.Info.HasTraitInfo<ValuedInfo>())
+			assets.GetText = () => "$" + world.ActorsHavingTrait<Valued>()
+				.Where(a => a.Owner == player && !a.IsDead)
 				.Sum(a => a.Info.TraitInfos<ValuedInfo>().First().Cost);
 
 			var harvesters = template.Get<LabelWidget>("HARVESTERS");
-			harvesters.GetText = () => world.Actors.Count(a => a.Owner == player && !a.IsDead && a.Info.HasTraitInfo<HarvesterInfo>()).ToString();
+			harvesters.GetText = () => world.ActorsHavingTrait<Harvester>().Count(a => a.Owner == player && !a.IsDead).ToString();
 
 			return template;
 		}
@@ -280,7 +280,7 @@ namespace OpenRA.Mods.Common.Widgets.Logic
 		{
 			return ScrollItemWidget.Setup(template, () => false, () =>
 			{
-				var playerBase = world.Actors.FirstOrDefault(a => !a.IsDead && a.Info.HasTraitInfo<BaseBuildingInfo>() && a.Owner == player);
+				var playerBase = world.ActorsHavingTrait<BaseBuilding>().FirstOrDefault(a => !a.IsDead && a.Owner == player);
 				if (playerBase != null)
 					worldRenderer.Viewport.Center(playerBase.CenterPosition);
 			});
diff --git a/OpenRA.Mods.Common/Widgets/StrategicProgressWidget.cs b/OpenRA.Mods.Common/Widgets/StrategicProgressWidget.cs
index 2f60452728..602da6322e 100644
--- a/OpenRA.Mods.Common/Widgets/StrategicProgressWidget.cs
+++ b/OpenRA.Mods.Common/Widgets/StrategicProgressWidget.cs
@@ -47,9 +47,9 @@ namespace OpenRA.Mods.Common.Widgets
 			{
 				WidgetUtils.DrawRGBA(ChromeProvider.GetImage("strategic", "critical_unowned"), offset + new float2(rb.Left + curX, rb.Top));
 
-				if (world.LocalPlayer != null && WorldUtils.AreMutualAllies(a.Actor.Owner, world.LocalPlayer))
+				if (world.LocalPlayer != null && WorldUtils.AreMutualAllies(a.Owner, world.LocalPlayer))
 					WidgetUtils.DrawRGBA(ChromeProvider.GetImage("strategic", "player_owned"), offset + new float2(rb.Left + curX, rb.Top));
-				else if (!a.Actor.Owner.NonCombatant)
+				else if (!a.Owner.NonCombatant)
 					WidgetUtils.DrawRGBA(ChromeProvider.GetImage("strategic", "enemy_owned"), offset + new float2(rb.Left + curX, rb.Top));
 
 				curX += 32;
@@ -96,8 +96,8 @@ namespace OpenRA.Mods.Common.Widgets
 
 		void Init()
 		{
-			var visible = world.ActorsWithTrait<StrategicVictoryConditions>().Any() &&
-				world.ActorsWithTrait<StrategicPoint>().Any();
+			var visible = world.ActorsHavingTrait<StrategicVictoryConditions>().Any() &&
+				world.ActorsHavingTrait<StrategicPoint>().Any();
 
 			IsVisible = () => visible;
 			initialised = true;
diff --git a/OpenRA.Mods.Common/Widgets/WorldCommandWidget.cs b/OpenRA.Mods.Common/Widgets/WorldCommandWidget.cs
index 3f3af3ccf0..10c96d78f9 100644
--- a/OpenRA.Mods.Common/Widgets/WorldCommandWidget.cs
+++ b/OpenRA.Mods.Common/Widgets/WorldCommandWidget.cs
@@ -193,16 +193,14 @@ namespace OpenRA.Mods.Common.Widgets
 		{
 			var player = world.RenderPlayer ?? world.LocalPlayer;
 
-			var bases = world.ActorsWithTrait<BaseBuilding>()
-				.Where(a => a.Actor.Owner == player)
-				.Select(b => b.Actor)
+			var bases = world.ActorsHavingTrait<BaseBuilding>()
+				.Where(a => a.Owner == player)
 				.ToList();
 
 			// If no BaseBuilding exist pick the first selectable Building.
 			if (!bases.Any())
 			{
-				var building = world.ActorsWithTrait<Building>()
-					.Select(b => b.Actor)
+				var building = world.ActorsHavingTrait<Building>()
 					.FirstOrDefault(a => a.Owner == player && a.Info.HasTraitInfo<SelectableInfo>());
 
 				// No buildings left
@@ -230,10 +228,9 @@ namespace OpenRA.Mods.Common.Widgets
 		{
 			var player = world.RenderPlayer ?? world.LocalPlayer;
 
-			var facilities = world.ActorsWithTrait<Production>()
-				.Where(a => a.Actor.Owner == player && !a.Actor.Info.HasTraitInfo<BaseBuildingInfo>())
-				.OrderBy(f => f.Actor.Info.TraitInfo<ProductionInfo>().Produces.First())
-				.Select(b => b.Actor)
+			var facilities = world.ActorsHavingTrait<Production>()
+				.Where(a => a.Owner == player && !a.Info.HasTraitInfo<BaseBuildingInfo>())
+				.OrderBy(f => f.Info.TraitInfo<ProductionInfo>().Produces.First())
 				.ToList();
 
 			if (!facilities.Any())
diff --git a/OpenRA.Mods.D2k/Traits/Carryable.cs b/OpenRA.Mods.D2k/Traits/Carryable.cs
index e484a3e928..4dd906ef44 100644
--- a/OpenRA.Mods.D2k/Traits/Carryable.cs
+++ b/OpenRA.Mods.D2k/Traits/Carryable.cs
@@ -100,9 +100,8 @@ namespace OpenRA.Mods.D2k.Traits
 		public Actor GetClosestIdleCarrier()
 		{
 			// Find carriers
-			var carriers = self.World.ActorsWithTrait<Carryall>()
-				.Where(p => p.Actor.Owner == self.Owner && !p.Trait.IsBusy && p.Actor.IsInWorld)
-				.Select(h => h.Actor);
+			var carriers = self.World.ActorsHavingTrait<Carryall>(c => !c.IsBusy)
+				.Where(a => a.Owner == self.Owner && a.IsInWorld);
 
 			return carriers.ClosestTo(self);
 		}
diff --git a/OpenRA.Mods.D2k/Traits/Player/HarvesterInsurance.cs b/OpenRA.Mods.D2k/Traits/Player/HarvesterInsurance.cs
index fc947c7b03..d48535efc0 100644
--- a/OpenRA.Mods.D2k/Traits/Player/HarvesterInsurance.cs
+++ b/OpenRA.Mods.D2k/Traits/Player/HarvesterInsurance.cs
@@ -31,15 +31,15 @@ namespace OpenRA.Mods.D2k.Traits
 
 		public void TryActivate()
 		{
-			var harvesters = self.World.ActorsWithTrait<Harvester>().Where(x => x.Actor.Owner == self.Owner);
+			var harvesters = self.World.ActorsHavingTrait<Harvester>().Where(x => x.Owner == self.Owner);
 			if (harvesters.Any())
 				return;
 
-			var refineries = self.World.ActorsWithTrait<Refinery>().Where(x => x.Actor.Owner == self.Owner);
+			var refineries = self.World.ActorsHavingTrait<Refinery>().Where(x => x.Owner == self.Owner);
 			if (!refineries.Any())
 				return;
 
-			var refinery = refineries.First().Actor;
+			var refinery = refineries.First();
 			var delivery = refinery.Trait<FreeActorWithDelivery>();
 			delivery.DoDelivery(refinery.Location + delivery.Info.DeliveryOffset, delivery.Info.Actor,
 				delivery.Info.DeliveringActor);
diff --git a/OpenRA.Mods.D2k/Traits/World/WormManager.cs b/OpenRA.Mods.D2k/Traits/World/WormManager.cs
index 2df88515f4..78e8410257 100644
--- a/OpenRA.Mods.D2k/Traits/World/WormManager.cs
+++ b/OpenRA.Mods.D2k/Traits/World/WormManager.cs
@@ -48,7 +48,7 @@ namespace OpenRA.Mods.D2k.Traits
 		public WormManager(Actor self, WormManagerInfo info)
 		{
 			this.info = info;
-			spawnPointActors = Exts.Lazy(() => self.World.ActorsWithTrait<WormSpawner>().Select(x => x.Actor).ToArray());
+			spawnPointActors = Exts.Lazy(() => self.World.ActorsHavingTrait<WormSpawner>().ToArray());
 		}
 
 		public void Tick(Actor self)
diff --git a/OpenRA.Mods.RA/Traits/SupportPowers/GpsPower.cs b/OpenRA.Mods.RA/Traits/SupportPowers/GpsPower.cs
index 25512c8c18..e8612a11dc 100644
--- a/OpenRA.Mods.RA/Traits/SupportPowers/GpsPower.cs
+++ b/OpenRA.Mods.RA/Traits/SupportPowers/GpsPower.cs
@@ -70,7 +70,7 @@ namespace OpenRA.Mods.RA.Traits
 		void RefreshGranted()
 		{
 			Granted = actors.Count > 0 && Launched;
-			GrantedAllies = Owner.World.ActorsWithTrait<GpsWatcher>().Any(p => p.Actor.Owner.IsAlliedWith(Owner) && p.Trait.Granted);
+			GrantedAllies = Owner.World.ActorsHavingTrait<GpsWatcher>(g => g.Granted).Any(p => p.Owner.IsAlliedWith(Owner));
 
 			if (Granted || GrantedAllies)
 				Owner.Shroud.ExploreAll(Owner.World);