diff --git a/src/main/java/net/minestom/server/instance/InstanceContainer.java b/src/main/java/net/minestom/server/instance/InstanceContainer.java
index 72f71a6b7..c5122884e 100644
--- a/src/main/java/net/minestom/server/instance/InstanceContainer.java
+++ b/src/main/java/net/minestom/server/instance/InstanceContainer.java
@@ -1,5 +1,7 @@
 package net.minestom.server.instance;
 
+import it.unimi.dsi.fastutil.longs.Long2ObjectMap;
+import it.unimi.dsi.fastutil.longs.Long2ObjectOpenHashMap;
 import net.minestom.server.MinecraftServer;
 import net.minestom.server.coordinate.Point;
 import net.minestom.server.coordinate.Vec;
@@ -28,7 +30,6 @@ import org.jetbrains.annotations.Nullable;
 
 import java.util.*;
 import java.util.concurrent.CompletableFuture;
-import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.CopyOnWriteArrayList;
 import java.util.concurrent.locks.Lock;
 import java.util.concurrent.locks.ReadWriteLock;
@@ -49,7 +50,8 @@ public class InstanceContainer extends Instance {
     // the chunk generator used, can be null
     private ChunkGenerator chunkGenerator;
     // (chunk index -> chunk) map, contains all the chunks in the instance
-    private final Map<Long, Chunk> chunks = new ConcurrentHashMap<>();
+    // used as a monitor when access is required
+    private final Long2ObjectMap<Chunk> chunks = new Long2ObjectOpenHashMap<>();
     // contains all the chunks to remove during the next instance tick, should be synchronized
     protected final Set<Chunk> scheduledChunksToRemove = new HashSet<>();
 
@@ -251,7 +253,9 @@ public class InstanceContainer extends Instance {
     @Override
     public Chunk getChunk(int chunkX, int chunkZ) {
         final long index = ChunkUtils.getChunkIndex(chunkX, chunkZ);
-        return chunks.get(index);
+        synchronized (chunks) {
+            return chunks.get(index);
+        }
     }
 
     @Override
@@ -261,8 +265,7 @@ public class InstanceContainer extends Instance {
 
     @Override
     public @NotNull CompletableFuture<Void> saveChunksToStorage() {
-        Collection<Chunk> chunksCollection = chunks.values();
-        return chunkLoader.saveChunks(chunksCollection);
+        return chunkLoader.saveChunks(getChunks());
     }
 
     protected @NotNull CompletableFuture<@NotNull Chunk> retrieveChunk(int chunkX, int chunkZ) {
@@ -407,17 +410,17 @@ public class InstanceContainer extends Instance {
         InstanceContainer copiedInstance = new InstanceContainer(UUID.randomUUID(), getDimensionType());
         copiedInstance.srcInstance = this;
         copiedInstance.lastBlockChangeTime = lastBlockChangeTime;
+        synchronized (chunks) {
+            for (Chunk chunk : chunks.values()) {
+                final int chunkX = chunk.getChunkX();
+                final int chunkZ = chunk.getChunkZ();
 
-        for (Chunk chunk : chunks.values()) {
-            final int chunkX = chunk.getChunkX();
-            final int chunkZ = chunk.getChunkZ();
+                final Chunk copiedChunk = chunk.copy(copiedInstance, chunkX, chunkZ);
 
-            final Chunk copiedChunk = chunk.copy(copiedInstance, chunkX, chunkZ);
-
-            copiedInstance.cacheChunk(copiedChunk);
-            UPDATE_MANAGER.signalChunkLoad(copiedChunk);
+                copiedInstance.cacheChunk(copiedChunk);
+                UPDATE_MANAGER.signalChunkLoad(copiedChunk);
+            }
         }
-
         return copiedInstance;
     }
 
@@ -462,7 +465,9 @@ public class InstanceContainer extends Instance {
      */
     public void cacheChunk(@NotNull Chunk chunk) {
         final long index = ChunkUtils.getChunkIndex(chunk);
-        this.chunks.put(index, chunk);
+        synchronized (chunks) {
+            this.chunks.put(index, chunk);
+        }
     }
 
     @Override
@@ -482,7 +487,9 @@ public class InstanceContainer extends Instance {
      */
     @Override
     public @NotNull Collection<@NotNull Chunk> getChunks() {
-        return Collections.unmodifiableCollection(chunks.values());
+        synchronized (chunks) {
+            return List.copyOf(chunks.values());
+        }
     }
 
     /**
@@ -565,8 +572,10 @@ public class InstanceContainer extends Instance {
                 });
 
                 // Clear cache
-                this.chunks.remove(index);
-                synchronized (entitiesLock){
+                synchronized (chunks) {
+                    this.chunks.remove(index);
+                }
+                synchronized (entitiesLock) {
                     this.chunkEntities.remove(index);
                 }