diff --git a/src/main/java/net/minecraft/world/chunk/Chunk.java b/src/main/java/net/minecraft/world/chunk/Chunk.java
index a8022ae..73b360c 100644
--- a/src/main/java/net/minecraft/world/chunk/Chunk.java
+++ b/src/main/java/net/minecraft/world/chunk/Chunk.java
@@ -6,7 +6,6 @@
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.HashMap;
-import java.util.HashSet;
 import java.util.Iterator;
 import java.util.List;
 import java.util.Map;
@@ -19,7 +18,6 @@
 import gnu.trove.set.TByteSet;
 import gnu.trove.set.hash.TByteHashSet;
 import net.minecraft.block.Block;
-import net.minecraft.block.ITileEntityProvider;
 import net.minecraft.block.material.Material;
 import net.minecraft.command.IEntitySelector;
 import net.minecraft.crash.CrashReport;
@@ -54,6 +52,8 @@
 import org.ultramine.server.chunk.ChunkHash;
 import org.ultramine.server.chunk.IChunkDependency;
 import org.ultramine.server.chunk.PendingBlockUpdate;
+import org.ultramine.server.internal.LambdaHolder;
+import org.ultramine.server.util.WeakObjectPool;
 
 public class Chunk implements IChunkDependency
 {
@@ -1541,12 +1541,15 @@
 		}
 	}
 	
-	/* ======================================== ULTRAMINE START =====================================*/
-	
+	/*======================================== ULTRAMINE START =====================================*/
+
+	private static final WeakObjectPool<ShortObjMap<PendingBlockUpdate>> shortObjMapPool = new WeakObjectPool<>(LambdaHolder.newShortObjMap());
+	private static final WeakObjectPool<TreeSet<PendingBlockUpdate>> treeSetPool = new WeakObjectPool<>(LambdaHolder.newTreeSet());
+
 	private final ShortObjMap<TileEntity> fastTileEntityMap = HashShortObjMaps.newMutableMap();
 	private final TByteSet updateLightCoords = new TByteHashSet();
 	
-	private Set<PendingBlockUpdate> pendingUpdatesSet;
+	private ShortObjMap<PendingBlockUpdate> pendingUpdatesSet;
 	private TreeSet<PendingBlockUpdate> pendingUpdatesQueue;
 	
 	private ChunkBindState bindState = ChunkBindState.NONE;
@@ -1562,6 +1565,23 @@
 	private short entityWaterCount;
 	private short entityItemCount;
 	private short entityXPOrbCount;
+
+	private void releasePendingUpdatesSets()
+	{
+		if(pendingUpdatesQueue != null)
+		{
+			if(!pendingUpdatesSet.isEmpty())
+				pendingUpdatesSet.clear();
+			if(!pendingUpdatesQueue.isEmpty())
+				pendingUpdatesQueue.clear();
+
+			shortObjMapPool.release(pendingUpdatesSet);
+			treeSetPool.release(pendingUpdatesQueue);
+
+			pendingUpdatesSet = null;
+			pendingUpdatesQueue = null;
+		}
+	}
 	
 	private void convertTileEntityMap()
 	{
@@ -1582,14 +1602,11 @@
 		PendingBlockUpdate p = pendingUpdatesQueue.first();
 		if(p.scheduledTime <= time)
 		{
-			pendingUpdatesSet.remove(p);
+			pendingUpdatesSet.remove(p.getChunkCoordHash());
 			pendingUpdatesQueue.remove(p);
 			
-			if(pendingUpdatesQueue.size() == 0)
-			{
-				pendingUpdatesSet = null;
-				pendingUpdatesQueue = null;
-			}
+			if(pendingUpdatesQueue.isEmpty())
+				releasePendingUpdatesSets();
 
 			isModified = true;
 			return p;
@@ -1602,13 +1619,16 @@
 	{
 		if(pendingUpdatesQueue == null)
 		{
-			pendingUpdatesSet = new HashSet<PendingBlockUpdate>();
-			pendingUpdatesQueue = new TreeSet<PendingBlockUpdate>();
+			pendingUpdatesSet = shortObjMapPool.getOrCreateInstance();
+			pendingUpdatesQueue = treeSetPool.getOrCreateInstance();
 		}
-		
-		if(!check || !pendingUpdatesSet.contains(p))
+
+		PendingBlockUpdate prev = null;
+		if(!check || (prev = pendingUpdatesSet.get(p.getChunkCoordHash())) == null || !Block.isEqualTo(p.getBlock(), prev.getBlock()))
 		{
-			pendingUpdatesSet.add(p);
+			if(prev != null)
+				pendingUpdatesQueue.remove(prev);
+			pendingUpdatesSet.put(p.getChunkCoordHash(), p);
 			pendingUpdatesQueue.add(p);
 			isModified = true;
 		}
@@ -1810,5 +1830,6 @@
 			if(exbs != null)
 				exbs.free();
 		}
+		releasePendingUpdatesSets();
 	}
 }
diff --git a/src/main/java/org/ultramine/server/chunk/PendingBlockUpdate.java b/src/main/java/org/ultramine/server/chunk/PendingBlockUpdate.java
index adf1b52..dabc9d2 100644
--- a/src/main/java/org/ultramine/server/chunk/PendingBlockUpdate.java
+++ b/src/main/java/org/ultramine/server/chunk/PendingBlockUpdate.java
@@ -40,6 +40,11 @@
 		PendingBlockUpdate p = (PendingBlockUpdate)o;
 		return this.hash == p.hash && Block.isEqualTo(this.block, p.block);
 	}
+
+	public short getChunkCoordHash()
+	{
+		return hash;
+	}
 	
 	public int hashCode()
 	{
diff --git a/src/main/java/org/ultramine/server/internal/LambdaHolder.java b/src/main/java/org/ultramine/server/internal/LambdaHolder.java
index a6416e9..d34b795 100644
--- a/src/main/java/org/ultramine/server/internal/LambdaHolder.java
+++ b/src/main/java/org/ultramine/server/internal/LambdaHolder.java
@@ -2,11 +2,31 @@
 
 import net.minecraft.entity.Entity;
 import net.minecraft.tileentity.TileEntity;
+import net.openhft.koloboke.collect.map.ShortObjMap;
+import net.openhft.koloboke.collect.map.hash.HashShortObjMaps;
 
+import java.util.TreeSet;
 import java.util.function.Predicate;
+import java.util.function.Supplier;
 
+/** Java 8 features like lambdas must not be used in net.minecraft classes, so all lambdas used there, located here*/
 public class LambdaHolder
 {
 	public static final Predicate<?> ENTITY_REMOVAL_PREDICATE = o -> ((Entity)o).removeThisTick;
 	public static final Predicate<?> TILE_ENTITY_REMOVAL_PREDICATE = o -> ((TileEntity)o).removeThisTick;
+
+	private static final Supplier<TreeSet<?>> NEW_TREE_SET = TreeSet::new;
+	private static final Supplier<ShortObjMap<?>> NEW_SHORT_OBJ_MAP = HashShortObjMaps::newMutableMap;
+
+	@SuppressWarnings("unchecked")
+	public static <T> Supplier<TreeSet<T>> newTreeSet()
+	{
+		return (Supplier<TreeSet<T>>) (Object) NEW_TREE_SET;
+	}
+
+	@SuppressWarnings("unchecked")
+	public static <T> Supplier<ShortObjMap<T>> newShortObjMap()
+	{
+		return (Supplier<ShortObjMap<T>>) (Object) NEW_SHORT_OBJ_MAP;
+	}
 }
diff --git a/src/main/java/org/ultramine/server/util/WeakObjectPool.java b/src/main/java/org/ultramine/server/util/WeakObjectPool.java
new file mode 100644
index 0000000..e86c4ce
--- /dev/null
+++ b/src/main/java/org/ultramine/server/util/WeakObjectPool.java
@@ -0,0 +1,42 @@
+package org.ultramine.server.util;
+
+import java.lang.ref.WeakReference;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.function.Supplier;
+
+public class WeakObjectPool<T>
+{
+	private final List<WeakReference<T>> pool = new ArrayList<>();
+	private final Supplier<T> factory;
+	private final int limit;
+
+	public WeakObjectPool(Supplier<T> factory, int limit)
+	{
+		this.factory = factory;
+		this.limit = limit;
+	}
+
+	public WeakObjectPool(Supplier<T> factory)
+	{
+		this(factory, Integer.MAX_VALUE);
+	}
+
+	public T getOrCreateInstance()
+	{
+		for(int size; (size = pool.size()) != 0;)
+		{
+			T val = pool.remove(size - 1).get();
+			if(val != null)
+				return val;
+		}
+
+		return factory.get();
+	}
+
+	public void release(T val)
+	{
+		if(pool.size() < limit)
+			pool.add(new WeakReference<>(val));
+	}
+}