Index: L2GameClient.java
===================================================================
--- L2GameClient.java   (revision 895)
+++ L2GameClient.java   (working copy)
@@ -20,6 +20,8 @@
 import java.sql.Connection;
 import java.sql.PreparedStatement;
 import java.sql.ResultSet;
+import java.util.LinkedHashSet;
+import java.util.Set;
 import java.util.concurrent.ArrayBlockingQueue;
 import java.util.concurrent.Future;
 import java.util.concurrent.RejectedExecutionException;
@@ -116,6 +118,8 @@

    private final ArrayBlockingQueue<ReceivablePacket<L2GameClient>> _packetQueue;
    private final ReentrantLock _queueLock = new ReentrantLock();
+   protected final Set<ServerPacketSendThread> _serverPacketQueue;
+   protected final ReentrantLock _serverPacketQueueLock = new ReentrantLock();

    private int[][] trace;

@@ -128,6 +132,7 @@
        _stats = new ClientStats();

        _packetQueue = new ArrayBlockingQueue<>(Config.CLIENT_PACKET_QUEUE_SIZE);
+       _serverPacketQueue = new LinkedHashSet<>();

        try
        {
@@ -277,6 +282,11 @@
            return;
        }

+       if (gsp.waitForOtherPackets() > 0)
+       {
+           new ServerPacketSendThread(gsp).run();
+       }
+
        getConnection().sendPacket(gsp);
        gsp.runImpl();
    }
@@ -855,6 +865,56 @@
        }
    }

+   protected class ServerPacketSendThread extends Thread
+   {
+       L2GameServerPacket _packet;
+       protected ServerPacketSendThread(L2GameServerPacket packet)
+       {
+           _packet = packet;
+       }
+
+       @Override
+       public void run()
+       {
+           try
+           {
+               _serverPacketQueueLock.lock();
+
+               if (_serverPacketQueue.add(this))
+               {
+                   // Unlock because the thread is going to sleep, we dont want the lock to sleep too :P
+                   _serverPacketQueueLock.unlock();
+
+                   try
+                   {
+                       sleep(_packet.waitForOtherPackets());
+                   }
+                   catch (InterruptedException e)
+                   {
+                       _log.log(Level.WARNING, "Packet send interrupted while waiting: ", e);
+                   }
+
+                   getConnection().sendPacket(_packet);
+                   _packet.runImpl();
+
+                   // Lock again to make sure we properly remove this
+                   _serverPacketQueueLock.lock();
+                   _serverPacketQueue.remove(this);
+               }
+           }
+           finally
+           {
+               _serverPacketQueueLock.unlock();
+           }
+       }
+
+       @Override
+       public boolean equals(Object obj)
+       {
+           return _packet.equals(obj);
+       }
+   }
+
    protected class CleanupTask implements Runnable
    {
        @Override