diff --git a/src/ComponentStorage.cs b/src/ComponentStorage.cs
index f53a8a0..6edc876 100644
--- a/src/ComponentStorage.cs
+++ b/src/ComponentStorage.cs
@@ -10,11 +10,13 @@ internal class ComponentStorage : IDisposable
 	internal readonly NativeArray Components;
 	internal readonly NativeArray<Entity> EntityIDs;
 	internal readonly TypeId TypeId;
+	internal readonly int ElementSize;
 
 	private bool IsDisposed;
 
 	public ComponentStorage(TypeId typeId, int elementSize)
 	{
+		ElementSize = elementSize;
 		Components = new NativeArray(elementSize);
 		EntityIDs = new NativeArray<Entity>();
 		TypeId = typeId;
diff --git a/src/RelationStorage.cs b/src/RelationStorage.cs
index 40b64ef..d46d645 100644
--- a/src/RelationStorage.cs
+++ b/src/RelationStorage.cs
@@ -10,6 +10,7 @@ internal class RelationStorage
 {
 	internal NativeArray Relations;
 	internal NativeArray RelationDatas;
+	internal int ElementSize;
 	internal Dictionary<(Entity, Entity), int> Indices = new Dictionary<(Entity, Entity), int>(16);
 	internal Dictionary<Entity, IndexableSet<Entity>> OutRelationSets = new Dictionary<Entity, IndexableSet<Entity>>(16);
 	internal Dictionary<Entity, IndexableSet<Entity>> InRelationSets = new Dictionary<Entity, IndexableSet<Entity>>(16);
@@ -19,6 +20,7 @@ internal class RelationStorage
 
 	public RelationStorage(int relationDataSize)
 	{
+		ElementSize = relationDataSize;
 		Relations = new NativeArray(Unsafe.SizeOf<(Entity, Entity)>());
 		RelationDatas = new NativeArray(relationDataSize);
 	}
diff --git a/src/Snapshot.cs b/src/Snapshot.cs
index 0421406..25f9bad 100644
--- a/src/Snapshot.cs
+++ b/src/Snapshot.cs
@@ -8,20 +8,20 @@ namespace MoonTools.ECS;
 // TODO: we should implement a NativeDictionary that can be memcopied
 public class Snapshot : IDisposable
 {
-	private Dictionary<TypeId, ComponentSnapshot> ComponentSnapshots = new Dictionary<TypeId, ComponentSnapshot>();
+	private List<ComponentSnapshot> ComponentSnapshots = new List<ComponentSnapshot>();
 
+	// FIXME: we could just have a filter ID
 	private Dictionary<FilterSignature, List<Entity>> Filters = new Dictionary<FilterSignature, List<Entity>>();
 
-	private Dictionary<TypeId, RelationSnapshot> RelationSnapshots =
-		new Dictionary<TypeId, RelationSnapshot>();
+	private List<RelationSnapshot> RelationSnapshots = new List<RelationSnapshot>();
 
-	private Dictionary<Entity, IndexableSet<TypeId>> EntityRelationIndex =
-		new Dictionary<Entity, IndexableSet<TypeId>>();
+	private List<IndexableSet<TypeId>> EntityRelationIndex =
+		new List<IndexableSet<TypeId>>();
 
-	private Dictionary<Entity, IndexableSet<TypeId>> EntityComponentIndex =
-		new Dictionary<Entity, IndexableSet<TypeId>>();
+	private List<IndexableSet<TypeId>> EntityComponentIndex =
+		new List<IndexableSet<TypeId>>();
 
-	private Dictionary<Entity, string> EntityTags = new Dictionary<Entity, string>();
+	private List<string> EntityTags = new List<string>();
 
 	private IdAssigner EntityIdAssigner = new IdAssigner();
 
@@ -48,68 +48,71 @@ public class Snapshot : IDisposable
 
 		// clear all component storages in case any were created after snapshot
 		// FIXME: this can be eliminated via component discovery
-		foreach (var (typeId, componentStorage) in world.ComponentIndex)
+		foreach (var componentStorage in world.ComponentIndex)
 		{
 			componentStorage.Clear();
 		}
 
 		// clear all relation storages in case any were created after snapshot
 		// FIXME: this can be eliminated via component discovery
-		foreach (var (typeId, relationStorage) in world.RelationIndex)
+		foreach (var relationStorage in world.RelationIndex)
 		{
 			relationStorage.Clear();
 		}
 
-		// restore components
-		foreach (var (typeId, componentSnapshot) in ComponentSnapshots)
+		for (var i = 0; i < ComponentSnapshots.Count; i += 1)
 		{
-			var componentStorage = world.ComponentIndex[typeId];
-			componentSnapshot.Restore(componentStorage);
+			var componentStorage = world.ComponentIndex[i];
+			ComponentSnapshots[i].Restore(componentStorage);
 		}
 
 		// restore relation state
-		foreach (var (typeId, relationSnapshot) in RelationSnapshots)
+		for (var i = 0; i < RelationSnapshots.Count; i += 1)
 		{
-			var relationStorage = world.RelationIndex[typeId];
-			relationSnapshot.Restore(relationStorage);
+			var relationStorage = world.RelationIndex[i];
+			RelationSnapshots[i].Restore(relationStorage);
 		}
 
 		// restore entity relation index state
 		// FIXME: arghhhh this is so slow
 
-		foreach (var (id, relationTypeSet) in world.EntityRelationIndex)
+		foreach (var relationTypeSet in world.EntityRelationIndex)
 		{
 			relationTypeSet.Clear();
 		}
 
-		foreach (var (id, relationTypeSet) in EntityRelationIndex)
+		for (var i = 0; i < EntityRelationIndex.Count; i += 1)
 		{
+			var relationTypeSet = EntityRelationIndex[i];
+
 			foreach (var typeId in relationTypeSet)
 			{
-				world.EntityRelationIndex[id].Add(typeId);
+				world.EntityRelationIndex[i].Add(typeId);
 			}
 		}
 
 		// restore entity component index state
 		// FIXME: arrghghhh this is so slow
 
-		foreach (var (id, componentTypeSet) in world.EntityComponentIndex)
+		foreach (var componentTypeSet in world.EntityComponentIndex)
 		{
 			componentTypeSet.Clear();
 		}
 
-		foreach (var (id, componentTypeSet) in EntityComponentIndex)
+		for (var i = 0; i < EntityComponentIndex.Count; i += 1)
 		{
+			var componentTypeSet = EntityComponentIndex[i];
+
 			foreach (var typeId in componentTypeSet)
 			{
-				world.EntityComponentIndex[id].Add(typeId);
+				world.EntityComponentIndex[i].Add(typeId);
 			}
 		}
 
 		// restore entity tags
-		foreach (var (id, s) in EntityTags)
+		for (var i = 0; i < EntityTags.Count; i += 1)
 		{
-			world.EntityTags[id] = s;
+			world.EntityTags[i] = EntityTags[i];
 		}
 	}
 
@@ -125,55 +128,68 @@ public class Snapshot : IDisposable
 		}
 
 		// copy components
-		foreach (var (typeId, componentStorage) in world.ComponentIndex)
+		for (var i = ComponentSnapshots.Count; i < world.ComponentIndex.Count; i += 1)
 		{
-			TakeComponentSnapshot(typeId, componentStorage);
+			ComponentSnapshots.Add(new ComponentSnapshot(world.ComponentIndex[i].ElementSize));
+		}
+
+		for (var i = 0; i < world.ComponentIndex.Count; i += 1)
+		{
+			ComponentSnapshots[i].Take(world.ComponentIndex[i]);
 		}
 
 		// copy relations
-		foreach (var (typeId, relationStorage) in world.RelationIndex)
+		for (var i = RelationSnapshots.Count; i < world.RelationIndex.Count; i += 1)
 		{
-			TakeRelationSnapshot(typeId, relationStorage);
+			RelationSnapshots.Add(new RelationSnapshot(world.RelationIndex[i].ElementSize));
+		}
+
+		for (var i = 0; i < world.RelationIndex.Count; i += 1)
+		{
+			RelationSnapshots[i].Take(world.RelationIndex[i]);
+		}
+
+		// fill in missing index structures
+
+		for (var i = EntityComponentIndex.Count; i < world.EntityComponentIndex.Count; i += 1)
+		{
+			EntityComponentIndex.Add(new IndexableSet<TypeId>());
+		}
+
+		for (var i = EntityRelationIndex.Count; i < world.EntityRelationIndex.Count; i += 1)
+		{
+			EntityRelationIndex.Add(new IndexableSet<TypeId>());
 		}
 
 		// copy entity relation index
 		// FIXME: arghhhh this is so slow
-		foreach (var (id, relationTypeSet) in world.EntityRelationIndex)
+		for (var i = 0; i < world.EntityRelationIndex.Count; i += 1)
 		{
-			if (!EntityRelationIndex.ContainsKey(id))
-			{
-				EntityRelationIndex.Add(id, new IndexableSet<TypeId>());
-			}
+			EntityRelationIndex[i].Clear();
 
-			EntityRelationIndex[id].Clear();
-
-			foreach (var typeId in relationTypeSet)
+			foreach (var typeId in world.EntityRelationIndex[i])
 			{
-				EntityRelationIndex[id].Add(typeId);
+				EntityRelationIndex[i].Add(typeId);
 			}
 		}
 
 		// copy entity component index
 		// FIXME: arghhhh this is so slow
-		foreach (var (id, componentTypeSet) in world.EntityComponentIndex)
+		for (var i = 0; i < world.EntityComponentIndex.Count; i += 1)
 		{
-			if (!EntityComponentIndex.ContainsKey(id))
-			{
-				EntityComponentIndex.Add(id, new IndexableSet<TypeId>());
-			}
+			EntityComponentIndex[i].Clear();
 
-			EntityComponentIndex[id].Clear();
-
-			foreach (var typeId in componentTypeSet)
+			foreach (var typeId in world.EntityComponentIndex[i])
 			{
-				EntityComponentIndex[id].Add(typeId);
+				EntityComponentIndex[i].Add(typeId);
 			}
 		}
 
 		// copy entity tags
-		foreach (var (id, s) in world.EntityTags)
+		EntityTags.Clear();
+		foreach (var s in world.EntityTags)
 		{
-			EntityTags[id] = s;
+			EntityTags.Add(s);
 		}
 	}
 
@@ -193,28 +209,6 @@ public class Snapshot : IDisposable
 		}
 	}
 
-	private void TakeComponentSnapshot(TypeId typeId, ComponentStorage componentStorage)
-	{
-		if (!ComponentSnapshots.TryGetValue(typeId, out var componentSnapshot))
-		{
-			componentSnapshot = new ComponentSnapshot(componentStorage.Components.ElementSize);
-			ComponentSnapshots.Add(typeId, componentSnapshot);
-		}
-
-		componentSnapshot.Take(componentStorage);
-	}
-
-	private void TakeRelationSnapshot(TypeId typeId, RelationStorage relationStorage)
-	{
-		if (!RelationSnapshots.TryGetValue(typeId, out var snapshot))
-		{
-			snapshot = new RelationSnapshot(relationStorage.RelationDatas.ElementSize);
-			RelationSnapshots.Add(typeId, snapshot);
-		}
-
-		snapshot.Take(relationStorage);
-	}
-
 	private class ComponentSnapshot : IDisposable
 	{
 		private readonly NativeArray Components;
@@ -348,22 +342,22 @@ public class Snapshot : IDisposable
 		{
 			if (disposing)
 			{
-				foreach (var componentSnapshot in ComponentSnapshots.Values)
+				foreach (var componentSnapshot in ComponentSnapshots)
 				{
 					componentSnapshot.Dispose();
 				}
 
-				foreach (var relationSnapshot in RelationSnapshots.Values)
+				foreach (var relationSnapshot in RelationSnapshots)
 				{
 					relationSnapshot.Dispose();
 				}
 
-				foreach (var componentSet in EntityComponentIndex.Values)
+				foreach (var componentSet in EntityComponentIndex)
 				{
 					componentSet.Dispose();
 				}
 
-				foreach (var relationSet in EntityRelationIndex.Values)
+				foreach (var relationSet in EntityRelationIndex)
 				{
 					relationSet.Dispose();
 				}
diff --git a/src/TypeId.cs b/src/TypeId.cs
index 62bc5d6..53c785f 100644
--- a/src/TypeId.cs
+++ b/src/TypeId.cs
@@ -1,4 +1,5 @@
 using System;
+using System.Runtime.CompilerServices;
 
 namespace MoonTools.ECS;
 
@@ -8,4 +9,74 @@ public readonly record struct TypeId(uint Value) : IComparable<TypeId>
 	{
 		return Value.CompareTo(other.Value);
 	}
+
+	public static implicit operator int(TypeId typeId)
+	{
+		return (int) typeId.Value;
+	}
+}
+
+public class ComponentTypeIdAssigner
+{
+	protected static ushort Counter;
+}
+
+public class ComponentTypeIdAssigner<T> : ComponentTypeIdAssigner
+{
+	public static readonly ushort Id;
+	public static readonly int Size;
+
+	[MethodImpl(MethodImplOptions.AggressiveInlining)]
+	static ComponentTypeIdAssigner()
+	{
+		Id = Counter++;
+		Size = Unsafe.SizeOf<T>();
+
+		World.ComponentTypeElementSizes.Add(Size);
+
+		#if DEBUG
+		World.ComponentTypeToId[typeof(T)] = new TypeId(Id);
+		World.ComponentTypeIdToType.Add(typeof(T));
+		#endif
+	}
+}
+
+public class RelationTypeIdAssigner
+{
+	protected static ushort Counter;
+}
+
+public class RelationTypeIdAssigner<T> : RelationTypeIdAssigner
+{
+	public static readonly ushort Id;
+	public static readonly int Size;
+
+	[MethodImpl(MethodImplOptions.AggressiveInlining)]
+	static RelationTypeIdAssigner()
+	{
+		Id = Counter++;
+		Size = Unsafe.SizeOf<T>();
+
+		World.RelationTypeElementSizes.Add(Size);
+	}
+}
+
+public class MessageTypeIdAssigner
+{
+	protected static ushort Counter;
+}
+
+public class MessageTypeIdAssigner<T> : MessageTypeIdAssigner
+{
+	public static readonly ushort Id;
+	public static readonly int Size;
+
+	[MethodImpl(MethodImplOptions.AggressiveInlining)]
+	static MessageTypeIdAssigner()
+	{
+		Id = Counter++;
+		Size = Unsafe.SizeOf<T>();
+
+		World.MessageTypeElementSizes.Add(Size);
+	}
 }
diff --git a/src/World.cs b/src/World.cs
index 70aad7d..753d0b7 100644
--- a/src/World.cs
+++ b/src/World.cs
@@ -7,85 +7,64 @@ namespace MoonTools.ECS;
 
 public class World : IDisposable
 {
-	// Get TypeId from a Type
-	private readonly Dictionary<Type, TypeId> TypeToId = new Dictionary<Type, TypeId>();
-
 #if DEBUG
-	private Dictionary<TypeId, Type> IdToType = new Dictionary<TypeId, Type>();
+	// TODO: is there a smarter way to do this?
+	internal static Dictionary<Type, TypeId> ComponentTypeToId = new Dictionary<Type, TypeId>();
+	internal static List<Type> ComponentTypeIdToType = new List<Type>();
 #endif
 
-	// Get element size from a TypeId
-	private readonly Dictionary<TypeId, int> ElementSizes = new Dictionary<TypeId, int>();
+	internal static List<int> ComponentTypeElementSizes = new List<int>();
+	internal static List<int> RelationTypeElementSizes = new List<int>();
+	internal static List<int> MessageTypeElementSizes = new List<int>();
 
 	// Filters
 	internal readonly Dictionary<FilterSignature, Filter> FilterIndex = new Dictionary<FilterSignature, Filter>();
-	private readonly Dictionary<TypeId, List<Filter>> TypeToFilter = new Dictionary<TypeId, List<Filter>>();
+	private readonly List<List<Filter>> ComponentTypeToFilter = new List<List<Filter>>();
 
 	// TODO: can we make the tag an native array of chars at some point?
-	internal Dictionary<Entity, string> EntityTags = new Dictionary<Entity, string>();
+	internal List<string> EntityTags = new List<string>();
 
 	// Relation Storages
-	internal Dictionary<TypeId, RelationStorage> RelationIndex = new Dictionary<TypeId, RelationStorage>();
-	internal Dictionary<Entity, IndexableSet<TypeId>> EntityRelationIndex = new Dictionary<Entity, IndexableSet<TypeId>>();
+	internal List<RelationStorage> RelationIndex = new List<RelationStorage>();
+	internal List<IndexableSet<TypeId>> EntityRelationIndex = new List<IndexableSet<TypeId>>();
 
 	// Message Storages
-	private Dictionary<TypeId, MessageStorage> MessageIndex = new Dictionary<TypeId, MessageStorage>();
+	private List<MessageStorage> MessageIndex = new List<MessageStorage>();
 
 	public FilterBuilder FilterBuilder => new FilterBuilder(this);
 
-	internal readonly Dictionary<TypeId, ComponentStorage> ComponentIndex = new Dictionary<TypeId, ComponentStorage>();
-	internal Dictionary<Entity, IndexableSet<TypeId>> EntityComponentIndex = new Dictionary<Entity, IndexableSet<TypeId>>();
+	internal readonly List<ComponentStorage> ComponentIndex = new List<ComponentStorage>();
+	internal List<IndexableSet<TypeId>> EntityComponentIndex = new List<IndexableSet<TypeId>>();
 
 	internal IdAssigner EntityIdAssigner = new IdAssigner();
-	private IdAssigner TypeIdAssigner = new IdAssigner();
 
 	private bool IsDisposed;
 
-	internal TypeId GetTypeId<T>() where T : unmanaged
-	{
-		if (TypeToId.ContainsKey(typeof(T)))
-		{
-			return TypeToId[typeof(T)];
-		}
-
-		var typeId = new TypeId(TypeIdAssigner.Assign());
-		TypeToId.Add(typeof(T), typeId);
-		ElementSizes.Add(typeId, Unsafe.SizeOf<T>());
-
-#if DEBUG
-		IdToType.Add(typeId, typeof(T));
-#endif
-
-		return typeId;
-	}
-
 	internal TypeId GetComponentTypeId<T>() where T : unmanaged
 	{
-		var typeId = GetTypeId<T>();
-		if (ComponentIndex.TryGetValue(typeId, out var componentStorage))
+		var typeId = new TypeId(ComponentTypeIdAssigner<T>.Id);
+		if (typeId < ComponentIndex.Count)
 		{
 			return typeId;
 		}
 
-		componentStorage = new ComponentStorage(typeId, ElementSizes[typeId]);
-		ComponentIndex.Add(typeId, componentStorage);
-		TypeToFilter.Add(typeId, new List<Filter>());
+		// add missing storages, it's possible for there to be multiples in multi-world scenarios
+		for (var i = ComponentIndex.Count; i <= typeId; i += 1)
+		{
+			var missingTypeId = new TypeId((uint) i);
+			var componentStorage = new ComponentStorage(missingTypeId, ComponentTypeElementSizes[i]);
+			ComponentIndex.Add(componentStorage);
+			ComponentTypeToFilter.Add(new List<Filter>());
+		}
+
 		return typeId;
 	}
 
 	[MethodImpl(MethodImplOptions.AggressiveInlining)]
 	private ComponentStorage GetComponentStorage<T>() where T : unmanaged
 	{
-		var typeId = GetTypeId<T>();
-		if (ComponentIndex.TryGetValue(typeId, out var componentStorage))
-		{
-			return componentStorage;
-		}
-
-		componentStorage = new ComponentStorage(typeId, ElementSizes[typeId]);
-		ComponentIndex.Add(typeId, componentStorage);
-		TypeToFilter.Add(typeId, new List<Filter>());
-		return componentStorage;
+		var typeId = GetComponentTypeId<T>();
+		return ComponentIndex[typeId];
 	}
 
 	// FILTERS
@@ -98,12 +77,12 @@ public class World : IDisposable
 
 			foreach (var typeId in signature.Included)
 			{
-				TypeToFilter[typeId].Add(filter);
+				ComponentTypeToFilter[(int) typeId.Value].Add(filter);
 			}
 
 			foreach (var typeId in signature.Excluded)
 			{
-				TypeToFilter[typeId].Add(filter);
+				ComponentTypeToFilter[(int) typeId.Value].Add(filter);
 			}
 
 			FilterIndex.Add(signature, filter);
@@ -118,50 +97,52 @@ public class World : IDisposable
 	{
 		var entity = new Entity(EntityIdAssigner.Assign());
 
-		if (!EntityComponentIndex.ContainsKey(entity))
+		if (entity.ID == EntityComponentIndex.Count)
 		{
-			EntityRelationIndex.Add(entity, new IndexableSet<TypeId>());
-			EntityComponentIndex.Add(entity, new IndexableSet<TypeId>());
+			EntityRelationIndex.Add(new IndexableSet<TypeId>());
+			EntityComponentIndex.Add(new IndexableSet<TypeId>());
+			EntityTags.Add(tag);
 		}
 
-		EntityTags[entity] = tag;
-
 		return entity;
 	}
 
 	public void Tag(Entity entity, string tag)
 	{
-		EntityTags[entity] = tag;
+		EntityTags[(int) entity.ID] = tag;
 	}
 
 	public string GetTag(Entity entity)
 	{
-		return EntityTags[entity];
+		return EntityTags[(int) entity.ID];
 	}
 
 	public void Destroy(in Entity entity)
 	{
+		var componentSet = EntityComponentIndex[(int) entity.ID];
+		var relationSet = EntityRelationIndex[(int) entity.ID];
+
 		// remove all components from storages
-		foreach (var componentTypeIndex in EntityComponentIndex[entity])
+		foreach (var componentTypeIndex in componentSet)
 		{
 			var componentStorage = ComponentIndex[componentTypeIndex];
 			componentStorage.Remove(entity);
 
-			foreach (var filter in TypeToFilter[componentTypeIndex])
+			foreach (var filter in ComponentTypeToFilter[componentTypeIndex])
 			{
 				filter.RemoveEntity(entity);
 			}
 		}
 
 		// remove all relations from storage
-		foreach (var relationTypeIndex in EntityRelationIndex[entity])
+		foreach (var relationTypeIndex in relationSet)
 		{
 			var relationStorage = RelationIndex[relationTypeIndex];
 			relationStorage.RemoveEntity(entity);
 		}
 
-		EntityComponentIndex[entity].Clear();
-		EntityRelationIndex[entity].Clear();
+		componentSet.Clear();
+		relationSet.Clear();
 
 		// recycle ID
 		EntityIdAssigner.Unassign(entity.ID);
@@ -177,7 +158,7 @@ public class World : IDisposable
 
 	internal bool Has(in Entity entity, in TypeId typeId)
 	{
-		return EntityComponentIndex[entity].Contains(typeId);
+		return EntityComponentIndex[(int) entity.ID].Contains(typeId);
 	}
 
 	public bool Some<T>() where T : unmanaged
@@ -210,9 +191,9 @@ public class World : IDisposable
 
 		if (!componentStorage.Set(entity, component))
 		{
-			EntityComponentIndex[entity].Add(componentStorage.TypeId);
+			EntityComponentIndex[(int) entity.ID].Add(componentStorage.TypeId);
 
-			foreach (var filter in TypeToFilter[componentStorage.TypeId])
+			foreach (var filter in ComponentTypeToFilter[componentStorage.TypeId])
 			{
 				filter.Check(entity);
 			}
@@ -225,9 +206,9 @@ public class World : IDisposable
 
 		if (componentStorage.Remove(entity))
 		{
-			EntityComponentIndex[entity].Remove(componentStorage.TypeId);
+			EntityComponentIndex[(int) entity.ID].Remove(componentStorage.TypeId);
 
-			foreach (var filter in TypeToFilter[componentStorage.TypeId])
+			foreach (var filter in ComponentTypeToFilter[componentStorage.TypeId])
 			{
 				filter.Check(entity);
 			}
@@ -236,31 +217,29 @@ public class World : IDisposable
 
 	// RELATIONS
 
-	private RelationStorage RegisterRelationType(TypeId typeId)
-	{
-		var relationStorage = new RelationStorage(ElementSizes[typeId]);
-		RelationIndex.Add(typeId, relationStorage);
-		return relationStorage;
-	}
-
 	[MethodImpl(MethodImplOptions.AggressiveInlining)]
 	private RelationStorage GetRelationStorage<T>() where T : unmanaged
 	{
-		var typeId = GetTypeId<T>();
-		if (RelationIndex.TryGetValue(typeId, out var relationStorage))
+		var typeId = new TypeId(RelationTypeIdAssigner<T>.Id);
+		if (typeId.Value < RelationIndex.Count)
 		{
-			return relationStorage;
+			return RelationIndex[typeId];
 		}
 
-		return RegisterRelationType(typeId);
+		for (var i = RelationIndex.Count; i <= typeId; i += 1)
+		{
+			RelationIndex.Add(new RelationStorage(RelationTypeElementSizes[i]));
+		}
+
+		return RelationIndex[typeId];
 	}
 
 	public void Relate<T>(in Entity entityA, in Entity entityB, in T relation) where T : unmanaged
 	{
 		var relationStorage = GetRelationStorage<T>();
 		relationStorage.Set(entityA, entityB, relation);
-		EntityRelationIndex[entityA].Add(TypeToId[typeof(T)]);
-		EntityRelationIndex[entityB].Add(TypeToId[typeof(T)]);
+		EntityRelationIndex[(int) entityA.ID].Add(new TypeId(RelationTypeIdAssigner<T>.Id));
+		EntityRelationIndex[(int) entityB.ID].Add(new TypeId(RelationTypeIdAssigner<T>.Id));
 	}
 
 	public void Unrelate<T>(in Entity entityA, in Entity entityB) where T : unmanaged
@@ -355,52 +334,52 @@ public class World : IDisposable
 
 	// MESSAGES
 
-	private TypeId GetMessageTypeId<T>() where T : unmanaged
+	private MessageStorage GetMessageStorage<T>() where T : unmanaged
 	{
-		var typeId = GetTypeId<T>();
+		var typeId = new TypeId(MessageTypeIdAssigner<T>.Id);
 
-		if (!MessageIndex.ContainsKey(typeId))
+		if (typeId < MessageIndex.Count)
 		{
-			MessageIndex.Add(typeId, new MessageStorage(Unsafe.SizeOf<T>()));
+			return MessageIndex[typeId];
 		}
 
-		return typeId;
+		for (var i = MessageIndex.Count; i <= typeId; i += 1)
+		{
+			MessageIndex.Add(new MessageStorage(MessageTypeElementSizes[i]));
+		}
+
+		return MessageIndex[typeId];
 	}
 
 	public void Send<T>(in T message) where T : unmanaged
 	{
-		var typeId = GetMessageTypeId<T>();
-		MessageIndex[typeId].Add(message);
+		GetMessageStorage<T>().Add(message);
 	}
 
 	public bool SomeMessage<T>() where T : unmanaged
 	{
-		var typeId = GetMessageTypeId<T>();
-		return MessageIndex[typeId].Some();
+		return GetMessageStorage<T>().Some();
 	}
 
 	public ReadOnlySpan<T> ReadMessages<T>() where T : unmanaged
 	{
-		var typeId = GetMessageTypeId<T>();
-		return MessageIndex[typeId].All<T>();
+		return GetMessageStorage<T>().All<T>();
 	}
 
 	public T ReadMessage<T>() where T : unmanaged
 	{
-		var typeId = GetMessageTypeId<T>();
-		return MessageIndex[typeId].First<T>();
+		return GetMessageStorage<T>().First<T>();
 	}
 
 	public void ClearMessages<T>() where T : unmanaged
 	{
-		var typeId = GetMessageTypeId<T>();
-		MessageIndex[typeId].Clear();
+		GetMessageStorage<T>().Clear();
 	}
 
 	// TODO: temporary component storage?
 	public void FinishUpdate()
 	{
-		foreach (var (_, messageStorage) in MessageIndex)
+		foreach (var messageStorage in MessageIndex)
 		{
 			messageStorage.Clear();
 		}
@@ -412,18 +391,18 @@ public class World : IDisposable
 #if DEBUG
 	public ComponentTypeEnumerator Debug_GetAllComponentTypes(Entity entity)
 	{
-		return new ComponentTypeEnumerator(this, EntityComponentIndex[entity]);
+		return new ComponentTypeEnumerator(this, EntityComponentIndex[(int) entity.ID]);
 	}
 
 	public IEnumerable<Entity> Debug_GetEntities(Type componentType)
 	{
-		var storage = ComponentIndex[TypeToId[componentType]];
+		var storage = ComponentIndex[ComponentTypeToId[componentType]];
 		return storage.Debug_GetEntities();
 	}
 
 	public IEnumerable<Type> Debug_SearchComponentType(string typeString)
 	{
-		foreach (var type in TypeToId.Keys)
+		foreach (var type in ComponentTypeToId.Keys)
 		{
 			if (type.ToString().ToLower().Contains(typeString.ToLower()))
 			{
@@ -456,7 +435,7 @@ public class World : IDisposable
 			return ComponentIndex < Types.Count;
 		}
 
-		public Type Current => World.IdToType[Types[ComponentIndex]];
+		public Type Current => ComponentTypeIdToType[Types[ComponentIndex]];
 	}
 #endif
 
@@ -466,29 +445,29 @@ public class World : IDisposable
 		{
 			if (disposing)
 			{
-				foreach (var componentStorage in ComponentIndex.Values)
+				foreach (var componentStorage in ComponentIndex)
 				{
 					componentStorage.Dispose();
 				}
 
-				foreach (var relationStorage in RelationIndex.Values)
+				foreach (var relationStorage in RelationIndex)
 				{
 					relationStorage.Dispose();
 				}
 
-				foreach (var messageStorage in MessageIndex.Values)
+				foreach (var messageStorage in MessageIndex)
 				{
 					messageStorage.Dispose();
 				}
 
-				foreach (var typeSet in EntityComponentIndex.Values)
+				foreach (var componentSet in EntityComponentIndex)
 				{
-					typeSet.Dispose();
+					componentSet.Dispose();
 				}
 
-				foreach (var typeSet in EntityRelationIndex.Values)
+				foreach (var relationSet in EntityRelationIndex)
 				{
-					typeSet.Dispose();
+					relationSet.Dispose();
 				}
 
 				foreach (var filter in FilterIndex.Values)
@@ -497,7 +476,6 @@ public class World : IDisposable
 				}
 
 				EntityIdAssigner.Dispose();
-				TypeIdAssigner.Dispose();
 			}
 
 			IsDisposed = true;