diff --git a/src/EntityComponentReader.cs b/src/EntityComponentReader.cs
index efdf50d..e55f6dd 100644
--- a/src/EntityComponentReader.cs
+++ b/src/EntityComponentReader.cs
@@ -52,7 +52,7 @@ namespace MoonTools.ECS
 			return ComponentDepot.GetSingletonEntity<TComponent>();
 		}
 
-		protected IEnumerable<(Entity, Entity, TRelationKind)> Relations<TRelationKind>() where TRelationKind : unmanaged
+		protected ReverseSpanEnumerator<(Entity, Entity)> Relations<TRelationKind>() where TRelationKind : unmanaged
 		{
 			return RelationDepot.Relations<TRelationKind>();
 		}
@@ -64,7 +64,7 @@ namespace MoonTools.ECS
 
 		protected TRelationKind GetRelationData<TRelationKind>(in Entity a, in Entity b) where TRelationKind : unmanaged
 		{
-			return RelationDepot.Get<TRelationKind>(new Relation(a.ID, b.ID));
+			return RelationDepot.Get<TRelationKind>(a, b);
 		}
 
 		// relations go A->B, so given A, will give all entities in outgoing relations of this kind.
diff --git a/src/Relation.cs b/src/Relation.cs
deleted file mode 100644
index 6dccd3a..0000000
--- a/src/Relation.cs
+++ /dev/null
@@ -1,31 +0,0 @@
-using System;
-
-namespace MoonTools.ECS
-{
-	internal struct Relation : IEquatable<Relation>
-	{
-		public Entity A { get; }
-		public Entity B { get; }
-
-		internal Relation(Entity entityA, Entity entityB)
-		{
-			A = entityA;
-			B = entityB;
-		}
-
-		public override bool Equals(object? obj)
-		{
-			return obj is Relation relation && Equals(relation);
-		}
-
-		public bool Equals(Relation other)
-		{
-			return A.ID == other.A.ID && B.ID == other.B.ID;
-		}
-
-		public override int GetHashCode()
-		{
-			return HashCode.Combine(A.ID, B.ID);
-		}
-	}
-}
diff --git a/src/RelationDepot.cs b/src/RelationDepot.cs
index abea455..06bb2fe 100644
--- a/src/RelationDepot.cs
+++ b/src/RelationDepot.cs
@@ -36,19 +36,19 @@ namespace MoonTools.ECS
 			return (RelationStorage<TRelationKind>) storages[storageIndex];
 		}
 
-		public void Set<TRelationKind>(Relation relation, TRelationKind relationData) where TRelationKind : unmanaged
+		public void Set<TRelationKind>(in Entity entityA, in Entity entityB, TRelationKind relationData) where TRelationKind : unmanaged
 		{
-			Lookup<TRelationKind>().Set(relation, relationData);
+			Lookup<TRelationKind>().Set(entityA, entityB, relationData);
 		}
 
-		public TRelationKind Get<TRelationKind>(Relation relation) where TRelationKind : unmanaged
+		public TRelationKind Get<TRelationKind>(in Entity entityA, in Entity entityB) where TRelationKind : unmanaged
 		{
-			return Lookup<TRelationKind>().Get(relation);
+			return Lookup<TRelationKind>().Get(entityA, entityB);
 		}
 
-		public (bool, bool) Remove<TRelationKind>(Relation relation) where TRelationKind : unmanaged
+		public (bool, bool) Remove<TRelationKind>(in Entity entityA, in Entity entityB) where TRelationKind : unmanaged
 		{
-			return Lookup<TRelationKind>().Remove(relation);
+			return Lookup<TRelationKind>().Remove(entityA, entityB);
 		}
 
 		public void UnrelateAll<TRelationKind>(int entityID) where TRelationKind : unmanaged
@@ -56,14 +56,14 @@ namespace MoonTools.ECS
 			Lookup<TRelationKind>().UnrelateAll(entityID);
 		}
 
-		public IEnumerable<(Entity, Entity, TRelationKind)> Relations<TRelationKind>() where TRelationKind : unmanaged
+		public ReverseSpanEnumerator<(Entity, Entity)> Relations<TRelationKind>() where TRelationKind : unmanaged
 		{
 			return Lookup<TRelationKind>().All();
 		}
 
 		public bool Related<TRelationKind>(int idA, int idB) where TRelationKind : unmanaged
 		{
-			return Lookup<TRelationKind>().Has(new Relation(idA, idB));
+			return Lookup<TRelationKind>().Has((idA, idB));
 		}
 
 		public ReverseSpanEnumerator<Entity> OutRelations<TRelationKind>(int entityID) where TRelationKind : unmanaged
diff --git a/src/RelationStorage.cs b/src/RelationStorage.cs
index 7c522c5..a069768 100644
--- a/src/RelationStorage.cs
+++ b/src/RelationStorage.cs
@@ -19,32 +19,30 @@ namespace MoonTools.ECS
 	internal class RelationStorage<TRelation> : RelationStorage where TRelation : unmanaged
 	{
 		private int count = 0;
-		private Dictionary<Relation, int> indices = new Dictionary<Relation, int>(16);
-		private Relation[] relations = new Relation[16];
+		private Dictionary<(Entity, Entity), int> indices = new Dictionary<(Entity, Entity), int>(16);
+		private (Entity, Entity)[] relations = new (Entity, Entity)[16];
 		private TRelation[] relationDatas = new TRelation[16];
 		private Dictionary<int, IndexableSet<Entity>> outRelations = new Dictionary<int, IndexableSet<Entity>>(16);
 		private Dictionary<int, IndexableSet<Entity>> inRelations = new Dictionary<int, IndexableSet<Entity>>(16);
 		private Stack<IndexableSet<Entity>> listPool = new Stack<IndexableSet<Entity>>();
 
-		public IEnumerable<(Entity, Entity, TRelation)> All()
+		public ReverseSpanEnumerator<(Entity, Entity)> All()
 		{
-			for (var i = 0; i < count; i += 1)
-			{
-				var relation = relations[i];
-				yield return (relation.A, relation.B, relationDatas[i]);
-			}
+			return new ReverseSpanEnumerator<(Entity, Entity)>(new Span<(Entity, Entity)>(relations, 0, count));
 		}
 
-		public void Set(Relation relation, TRelation relationData)
+		public void Set(in Entity entityA, in Entity entityB, TRelation relationData)
 		{
+			var relation = (entityA, entityB);
+
 			if (indices.TryGetValue(relation, out var index))
 			{
 				relationDatas[index] = relationData;
 				return;
 			}
 
-			var idA = relation.A.ID;
-			var idB = relation.B.ID;
+			var idA = entityA.ID;
+			var idB = entityB.ID;
 
 			if (!outRelations.ContainsKey(idA))
 			{
@@ -70,12 +68,12 @@ namespace MoonTools.ECS
 			count += 1;
 		}
 
-		public TRelation Get(Relation relation)
+		public TRelation Get(in Entity entityA, in Entity entityB)
 		{
-			return relationDatas[indices[relation]];
+			return relationDatas[indices[(entityA, entityB)]];
 		}
 
-		public bool Has(Relation relation)
+		public bool Has((Entity, Entity) relation)
 		{
 			return indices.ContainsKey(relation);
 		}
@@ -147,24 +145,25 @@ namespace MoonTools.ECS
 			return inRelations.TryGetValue(entityID, out var entityInRelations) ? entityInRelations.Count : 0;
 		}
 
-		public (bool, bool) Remove(Relation relation)
+		public (bool, bool) Remove(in Entity entityA, in Entity entityB)
 		{
 			var aEmpty = false;
 			var bEmpty = false;
+			var relation = (entityA, entityB);
 
-			if (outRelations.TryGetValue(relation.A.ID, out var entityOutRelations))
+			if (outRelations.TryGetValue(entityA.ID, out var entityOutRelations))
 			{
-				entityOutRelations.Remove(relation.B.ID);
-				if (outRelations[relation.A.ID].Count == 0)
+				entityOutRelations.Remove(entityB.ID);
+				if (outRelations[entityA.ID].Count == 0)
 				{
 					aEmpty = true;
 				}
 			}
 
-			if (inRelations.TryGetValue(relation.B.ID, out var entityInRelations))
+			if (inRelations.TryGetValue(entityB.ID, out var entityInRelations))
 			{
-				entityInRelations.Remove(relation.A.ID);
-				if (inRelations[relation.B.ID].Count == 0)
+				entityInRelations.Remove(entityA.ID);
+				if (inRelations[entityB.ID].Count == 0)
 				{
 					bEmpty = true;
 				}
@@ -210,12 +209,12 @@ namespace MoonTools.ECS
 
 		public override unsafe void Set(int entityA, int entityB, void* relationData)
 		{
-			Set(new Relation(entityA, entityB), *((TRelation*) relationData));
+			Set(entityA, entityB, *((TRelation*) relationData));
 		}
 
 		public override int GetStorageIndex(int entityA, int entityB)
 		{
-			return indices[new Relation(entityA, entityB)];
+			return indices[(entityA, entityB)];
 		}
 
 		public override unsafe void* Get(int relationStorageIndex)
@@ -232,7 +231,7 @@ namespace MoonTools.ECS
 			{
 				foreach (var entityB in entityOutRelations)
 				{
-					Remove(new Relation(entityID, entityB));
+					Remove(entityID, entityB);
 				}
 
 				ReturnHashSetToPool(entityOutRelations);
@@ -243,7 +242,7 @@ namespace MoonTools.ECS
 			{
 				foreach (var entityA in entityInRelations)
 				{
-					Remove(new Relation(entityA, entityID));
+					Remove(entityA, entityID);
 				}
 
 				ReturnHashSetToPool(entityInRelations);
diff --git a/src/System.cs b/src/System.cs
index 35c44a6..37dd234 100644
--- a/src/System.cs
+++ b/src/System.cs
@@ -70,7 +70,7 @@ namespace MoonTools.ECS
 
 		protected void Relate<TRelationKind>(in Entity entityA, in Entity entityB, TRelationKind relationData) where TRelationKind : unmanaged
 		{
-			RelationDepot.Set<TRelationKind>(new Relation(entityA, entityB), relationData);
+			RelationDepot.Set(entityA, entityB, relationData);
 			var relationTypeIndex = RelationTypeIndices.GetIndex<TRelationKind>();
 			EntityStorage.AddRelationKind(entityA.ID, relationTypeIndex);
 			EntityStorage.AddRelationKind(entityB.ID, relationTypeIndex);
@@ -78,7 +78,7 @@ namespace MoonTools.ECS
 
 		protected void Unrelate<TRelationKind>(in Entity entityA, in Entity entityB) where TRelationKind : unmanaged
 		{
-			var (aEmpty, bEmpty) = RelationDepot.Remove<TRelationKind>(new Relation(entityA, entityB));
+			var (aEmpty, bEmpty) = RelationDepot.Remove<TRelationKind>(entityA, entityB);
 
 			if (aEmpty)
 			{
diff --git a/src/TemplateStorage.cs b/src/TemplateStorage.cs
index c45f32f..fb9dfa0 100644
--- a/src/TemplateStorage.cs
+++ b/src/TemplateStorage.cs
@@ -1,4 +1,4 @@
-using System.Collections.Generic;
+using System.Collections.Generic;
 
 namespace MoonTools.ECS
 {
@@ -19,7 +19,7 @@ namespace MoonTools.ECS
 			return TemplateToComponentTypeIndices[templateID].Add(componentTypeIndex);
 		}
 
-		public IEnumerable<int> ComponentTypeIndices(int templateID)
+		public HashSet<int> ComponentTypeIndices(int templateID)
 		{
 			return TemplateToComponentTypeIndices[templateID];
 		}