Some portion of optimizations:

* Clear outgoing packet queue after player disconnect
* Disable sleep between chunk saving
* Put 2x4096 bytes instead 2048x4 bytes for region file aligment
* Using map to search player by name instead iterating over all players
* Some tweaks for decorations (item frames, maps)

src/main/java/kcauldron/KCauldron.java

@@ -41,6 +41,8 @@ public class KCauldron {
                     sGroup = manifest.getProperty("KCauldron-Group");
                     sBranch = manifest.getProperty("KCauldron-Branch");
                     sChannel = manifest.getProperty("KCauldron-Channel");
+                    sLegacy = Boolean.parseBoolean(manifest.getProperty("KCauldron-Legacy"));
+                    sOfficial = Boolean.parseBoolean(manifest.getProperty("KCauldron-Official"));
                     break;
                 }
                 manifest.clear();
@@ -99,6 +101,18 @@ public class KCauldron {
         parseManifest();
         return sChannel;
     }
+    
+    private static boolean sLegacy, sOfficial;
+    
+    public static boolean isLegacy() {
+    	parseManifest();
+    	return sLegacy;
+    }
+    
+    public static boolean isOfficial() {
+    	parseManifest();
+    	return sOfficial;
+    }
 
     public static File sNewServerLocation;
     public static String sNewServerVersion;

src/main/java/kcauldron/updater/DefaultUpdateCallback.java

@@ -6,6 +6,7 @@ import kcauldron.updater.KVersionRetriever.IVersionCheckCallback;
 import net.minecraft.server.MinecraftServer;
 
 import org.bukkit.Bukkit;
+import org.bukkit.ChatColor;
 import org.bukkit.command.CommandSender;
 import org.bukkit.entity.Player;
 import org.bukkit.event.player.PlayerJoinEvent;
@@ -19,13 +20,21 @@ public class DefaultUpdateCallback implements IVersionCheckCallback {
 
     public void onPlayerJoin(PlayerJoinEvent event) {
         Player player = event.getPlayer();
-        if (mHasUpdate && hasPermission(player)) {
-            sendUpdate(player);
+        if (hasPermission(player)) {
+        	if (KCauldron.isLegacy()) {
+        		player.sendMessage(ChatColor.YELLOW + "We're running on legacy version on KCauldron, please update your version");
+        	}        	
+        	if (!KCauldron.isOfficial()) {
+        		player.sendMessage(ChatColor.YELLOW + "We're running on non-official version on KCauldron, please update your version");
+        	}        	
+            if (mHasUpdate) {
+                sendUpdate(player);
+            }
         }
     }
 
     private boolean hasPermission(CommandSender player) {
-        return player.hasPermission(KCauldronCommand.UPDATE);
+        return player.hasPermission(KCauldronCommand.UPDATE) || player.isOp();
     }
 
     private void sendUpdate(CommandSender player) {

src/main/java/kcauldron/updater/KVersionRetriever.java

@@ -83,6 +83,7 @@ public class KVersionRetriever implements Runnable, UncaughtExceptionHandler {
                     .get()
                     .setUri("https://api.prok.pw/repo/version/" + mGroup + "/"
                             + mName)
+                    .addParameter("version", KCauldron.getCurrentVersion())
                     .addParameter("hostname", sServer.getHostname())
                     .addParameter("port", "" + sServer.getPort()).build();
             HttpResponse response = HttpClientBuilder.create()

src/main/java/org/bukkit/craftbukkit/map/CraftMapRenderer.java

@@ -1,6 +1,9 @@
 package org.bukkit.craftbukkit.map;
 
 
+import java.util.Map;
+import java.util.UUID;
+
 import org.bukkit.Bukkit;
 import org.bukkit.entity.Player;
 import org.bukkit.map.MapCanvas;
@@ -8,6 +11,8 @@ import org.bukkit.map.MapCursorCollection;
 import org.bukkit.map.MapRenderer;
 import org.bukkit.map.MapView;
 
+import net.minecraft.world.storage.MapData;
+
 public class CraftMapRenderer extends MapRenderer {
 
     private final net.minecraft.world.storage.MapData worldMap;
@@ -32,14 +37,14 @@ public class CraftMapRenderer extends MapRenderer {
             cursors.removeCursor(cursors.getCursor(0));
         }
 
-        for (Object key : worldMap.playersVisibleOnMap.keySet()) {
+        for (Map.Entry<UUID, MapData.MapCoord> key : worldMap.playersVisibleOnMap.entrySet()) {
             // If this cursor is for a player check visibility with vanish system
-            Player other = Bukkit.getPlayerExact((String) key);
+            Player other = Bukkit.getPlayer(key.getKey());
             if (other != null && !player.canSee(other)) {
                 continue;
             }
 
-            net.minecraft.world.storage.MapData.MapCoord decoration = (net.minecraft.world.storage.MapData.MapCoord) worldMap.playersVisibleOnMap.get(key);
+            MapData.MapCoord decoration = key.getValue();
             cursors.addCursor(decoration.centerX, decoration.centerZ, (byte) (decoration.iconRotation & 15), decoration.iconSize);
         }
     }

src/main/java/org/spigotmc/CaseInsensitiveHashingStrategy.java

@@ -0,0 +1,18 @@
+package org.spigotmc;
+
+import gnu.trove.strategy.HashingStrategy;
+
+class CaseInsensitiveHashingStrategy implements HashingStrategy<String> {
+	private static final long serialVersionUID = -9212222772914758878L;
+	static final CaseInsensitiveHashingStrategy INSTANCE = new CaseInsensitiveHashingStrategy();
+
+    @Override
+    public int computeHashCode(String object) {
+        return object.toLowerCase().hashCode();
+    }
+
+    @Override
+    public boolean equals(String o1, String o2) {
+        return o1.equalsIgnoreCase(o2);
+    }
+}

src/main/java/org/spigotmc/CaseInsensitiveMap.java

@@ -0,0 +1,15 @@
+package org.spigotmc;
+
+import gnu.trove.map.hash.TCustomHashMap;
+import java.util.Map;
+
+public class CaseInsensitiveMap<V> extends TCustomHashMap<String, V> {
+
+    public CaseInsensitiveMap() {
+        super(CaseInsensitiveHashingStrategy.INSTANCE);
+    }
+
+    public CaseInsensitiveMap(Map<? extends String, ? extends V> map) {
+        super(CaseInsensitiveHashingStrategy.INSTANCE, map);
+    }
+}