diff --git a/packages/entity/index.js b/packages/entity/index.js
index 28e5bfc..0b2db5a 100644
--- a/packages/entity/index.js
+++ b/packages/entity/index.js
@@ -68,6 +68,7 @@ export class Entity extends decorate(Resource) {
     this.once('destroyed', () => {
       this.removeAllTraits();
     });
+    this.initializeSynchronizedChildren();
   }
 
   acceptPacket(packet) {
diff --git a/packages/entity/list/index.js b/packages/entity/list/index.js
index edf28ab..ec5606b 100644
--- a/packages/entity/list/index.js
+++ b/packages/entity/list/index.js
@@ -21,6 +21,7 @@ export class EntityList extends decorate(class {}) {
     this._entities = {};
     this._flatEntities = [];
     this._quadTree = new QuadTree();
+    this.initializeSynchronizedChildren();
   }
 
   *[Symbol.iterator]() {
@@ -117,10 +118,7 @@ export class EntityList extends decorate(class {}) {
       this.tickAfterDestructionTickers(elapsed);
     }
     // Run normal tickers.
-    for (let i = 0; i < this._flatEntities.length; i++) {
-      const entity = this._flatEntities[i];
-      entity.tick(elapsed);
-    }
+    this.tickEntities(elapsed)
     // Update state.
     if (AVOCADO_SERVER) {
       this.tickMutateState();
@@ -142,6 +140,13 @@ export class EntityList extends decorate(class {}) {
     }
   }
 
+  tickEntities(elapsed) {
+    for (let i = 0; i < this._flatEntities.length; i++) {
+      const entity = this._flatEntities[i];
+      entity.tick(elapsed);
+    }
+  }
+
   tickMutateState(state) {
     this.state = this.state.withMutations((state) => {
       for (let i = 0; i < this._dirtyEntities.length; i++) {
diff --git a/packages/entity/trait/index.js b/packages/entity/trait/index.js
index 8109818..470625d 100644
--- a/packages/entity/trait/index.js
+++ b/packages/entity/trait/index.js
@@ -19,6 +19,7 @@ export class Trait extends decorate(class {}) {
     this._memoizedListeners = undefined;
     this.params = I.fromJS(ctor.defaultParams()).merge(I.fromJS(params));
     this.state = I.fromJS(ctor.defaultState()).merge(I.fromJS(state));
+    this.initializeSynchronizedChildren();
   }
 
   destroy() {}
diff --git a/packages/state/synchronized.js b/packages/state/synchronized.js
index 17f3f08..047a258 100644
--- a/packages/state/synchronized.js
+++ b/packages/state/synchronized.js
@@ -14,6 +14,31 @@ export function Synchronized(Superclass) {
     constructor(...args) {
       super(...args);
       this.state = I.Map();
+      this._childrenWithState = []
+      this._childrenWithoutState = [];
+      this._childrenWithTickers = [];
+    }
+
+    initializeSynchronizedChildren() {
+      const synchronizedChildren = this.synchronizedChildren();
+      for (let i = 0; i < synchronizedChildren.length; ++i) {
+        const key = synchronizedChildren[i];
+        if (
+          'undefined' !== typeof this[key]
+          && 'undefined' !== typeof this[key].tick
+        ) {
+          this._childrenWithTickers.push(key);
+        }
+        if (
+          'undefined' !== typeof this[key]
+          && 'undefined' !== typeof this[key].state
+        ) {
+          this._childrenWithState.push(key);
+        }
+        else {
+          this._childrenWithoutState.push(key);
+        }
+      }
     }
 
     synchronizedChildren() {
@@ -59,33 +84,39 @@ export function Synchronized(Superclass) {
     }
 
     tick(elapsed) {
-      const children = this.synchronizedChildren();
-      for (let i = 0; i < children.length; ++i) {
-        const key = children[i];
-        if (
-          'undefined' !== typeof this[key]
-          && 'undefined' !== typeof this[key].tick
-        ) {
-          this[key].tick(elapsed);
-        }
+      for (let i = 0; i < this._childrenWithTickers.length; i++) {
+        const key = this._childrenWithTickers[i];
+        this[key].tick(elapsed);
       }
       if (AVOCADO_SERVER) {
-        this.state = this.state.withMutations((state) => {
-          for (let i = 0; i < children.length; ++i) {
-            const key = children[i];
-            if (
-              'undefined' !== typeof this[key]
-              && 'undefined' !== typeof this[key].state
-            ) {
-              state.set(key, this[key].state);
-            }
-            else {
-              state.set(key, this[key]);
-            }
-          }
-        });
+        this.tickMutateState();
       }
     }
 
+    prepareStateMutation() {
+      const mutation = {};
+      for (let i = 0; i < this._childrenWithState.length; i++) {
+        const key = this._childrenWithState[i];
+        mutation[key] = this[key].state;
+      }
+      for (let i = 0; i < this._childrenWithoutState.length; i++) {
+        const key = this._childrenWithoutState[i];
+        mutation[key] = this[key];
+      }
+    }
+
+    tickMutateState() {
+      this.state = this.state.withMutations((state) => {
+        for (let i = 0; i < this._childrenWithState.length; i++) {
+          const key = this._childrenWithState[i];
+          state.set(key, this[key].state);
+        }
+        for (let i = 0; i < this._childrenWithoutState.length; i++) {
+          const key = this._childrenWithoutState[i];
+          state.set(key, this[key]);
+        }
+      });
+    }
+
   }
 }
diff --git a/packages/topdown/layer.js b/packages/topdown/layer.js
index 71c9f9b..a8ce0d8 100644
--- a/packages/topdown/layer.js
+++ b/packages/topdown/layer.js
@@ -38,6 +38,7 @@ export class Layer extends decorate(class {}) {
     this.on('tilesetUriChanged', this.onTilesetUriChanged, this);
     this.onTilesetUriChanged();
     this.on('worldChanged', this.onWorldChanged, this);
+    this.initializeSynchronizedChildren();
   }
 
   addEntity(entity) {
diff --git a/packages/topdown/layers.js b/packages/topdown/layers.js
index 9c6724e..a340946 100644
--- a/packages/topdown/layers.js
+++ b/packages/topdown/layers.js
@@ -15,6 +15,7 @@ export class Layers extends decorate(class {}) {
   constructor() {
     super();
     this.layers = {};
+    this.initializeSynchronizedChildren();
   }
 
   *[Symbol.iterator]() {
diff --git a/packages/topdown/room.js b/packages/topdown/room.js
index dca7c23..1620f5c 100644
--- a/packages/topdown/room.js
+++ b/packages/topdown/room.js
@@ -34,6 +34,7 @@ export class Room extends decorate(class {}) {
     this.layers.on('layerAdded', this.onLayerAdded, this);
     this.on('sizeChanged', this.onSizeChanged, this);
     this.on('worldChanged', this.onWorldChanged, this);
+    this.initializeSynchronizedChildren();
   }
 
   addEntityToLayer(entity, layerIndex = 0) {
diff --git a/packages/topdown/tiles.js b/packages/topdown/tiles.js
index 34d3428..7843977 100644
--- a/packages/topdown/tiles.js
+++ b/packages/topdown/tiles.js
@@ -17,6 +17,7 @@ export class Tiles extends decorate(class {}) {
   constructor() {
     super();
     this.data = I.List();
+    this.initializeSynchronizedChildren();
   }
 
   forEachTile(fn) {