diff --git a/src/main/java/refinedstorage/api/storage/IGroupedStorage.java b/src/main/java/refinedstorage/api/storage/IGroupedStorage.java
index cf173150f..a31a78e01 100755
--- a/src/main/java/refinedstorage/api/storage/IGroupedStorage.java
+++ b/src/main/java/refinedstorage/api/storage/IGroupedStorage.java
@@ -19,9 +19,10 @@ public interface IGroupedStorage {
     /**
      * Adds an item to the network. Will merge it with another item if it already exists.
      *
-     * @param stack The stack to add, do NOT modify
+     * @param stack      The stack to add, do NOT modify
+     * @param rebuilding Whether this method is called while the storage is rebuilding
      */
-    void add(ItemStack stack);
+    void add(ItemStack stack, boolean rebuilding);
 
     /**
      * Removes a item from the network.
diff --git a/src/main/java/refinedstorage/apiimpl/storage/GroupedStorage.java b/src/main/java/refinedstorage/apiimpl/storage/GroupedStorage.java
index 4ebba6e50..6a93326f6 100755
--- a/src/main/java/refinedstorage/apiimpl/storage/GroupedStorage.java
+++ b/src/main/java/refinedstorage/apiimpl/storage/GroupedStorage.java
@@ -39,7 +39,7 @@ public class GroupedStorage implements IGroupedStorage {
 
         for (IStorage storage : storages) {
             for (ItemStack stack : storage.getItems()) {
-                add(stack);
+                add(stack, true);
             }
         }
 
@@ -47,7 +47,7 @@ public class GroupedStorage implements IGroupedStorage {
             for (ItemStack output : pattern.getOutputs()) {
                 ItemStack patternStack = output.copy();
                 patternStack.stackSize = 0;
-                add(patternStack);
+                add(patternStack, true);
             }
         }
 
@@ -55,12 +55,14 @@ public class GroupedStorage implements IGroupedStorage {
     }
 
     @Override
-    public void add(ItemStack stack) {
+    public void add(ItemStack stack, boolean rebuilding) {
         for (ItemStack otherStack : stacks.get(stack.getItem())) {
             if (RefinedStorageUtils.compareStackNoQuantity(otherStack, stack)) {
                 otherStack.stackSize += stack.stackSize;
 
-                network.sendStorageDeltaToClient(stack, stack.stackSize);
+                if (!rebuilding) {
+                    network.sendStorageDeltaToClient(stack, stack.stackSize);
+                }
 
                 return;
             }
@@ -68,7 +70,9 @@ public class GroupedStorage implements IGroupedStorage {
 
         stacks.put(stack.getItem(), stack.copy());
 
-        network.sendStorageDeltaToClient(stack, stack.stackSize);
+        if (!rebuilding) {
+            network.sendStorageDeltaToClient(stack, stack.stackSize);
+        }
     }
 
     @Override
diff --git a/src/main/java/refinedstorage/tile/controller/TileController.java b/src/main/java/refinedstorage/tile/controller/TileController.java
index e81337459..5b25f58f3 100755
--- a/src/main/java/refinedstorage/tile/controller/TileController.java
+++ b/src/main/java/refinedstorage/tile/controller/TileController.java
@@ -516,7 +516,7 @@ public class TileController extends TileBase implements INetworkMaster, IEnergyR
                 }
             }
 
-            storage.add(ItemHandlerHelper.copyStackWithSize(stack, inserted));
+            storage.add(ItemHandlerHelper.copyStackWithSize(stack, inserted), false);
         }
 
         return remainder;
diff --git a/src/main/java/refinedstorage/tile/externalstorage/ExternalStorage.java b/src/main/java/refinedstorage/tile/externalstorage/ExternalStorage.java
index 1c14f3428..19f7832c5 100755
--- a/src/main/java/refinedstorage/tile/externalstorage/ExternalStorage.java
+++ b/src/main/java/refinedstorage/tile/externalstorage/ExternalStorage.java
@@ -4,18 +4,19 @@ import net.minecraft.item.ItemStack;
 import refinedstorage.RefinedStorageUtils;
 import refinedstorage.api.storage.IStorage;
 
-import java.util.ArrayList;
 import java.util.List;
 
 public abstract class ExternalStorage implements IStorage {
-    private List<ItemStack> cache = new ArrayList<ItemStack>();
+    private List<ItemStack> cache;
 
     public abstract int getCapacity();
 
     public boolean updateCache() {
         List<ItemStack> items = getItems();
 
-        if (items.size() != cache.size()) {
+        if (cache == null) {
+            cache = items;
+        } else if (items.size() != cache.size()) {
             cache = items;
 
             return true;
diff --git a/src/main/java/refinedstorage/tile/externalstorage/TileExternalStorage.java b/src/main/java/refinedstorage/tile/externalstorage/TileExternalStorage.java
index d9cf2d2d8..d22304d3d 100755
--- a/src/main/java/refinedstorage/tile/externalstorage/TileExternalStorage.java
+++ b/src/main/java/refinedstorage/tile/externalstorage/TileExternalStorage.java
@@ -74,8 +74,6 @@ public class TileExternalStorage extends TileNode implements IStorageProvider, I
                 }
 
                 if (shouldRebuild) {
-                    System.out.println("Rebuilding ext storage");
-
                     network.getStorage().rebuild();
                 }
             }