Use FastUtil Long/Int HashMap's

For DataWatcher, swap out plain Integer key HashMap for a Int2ObjectOpenHashMap
For ChunkProviderServer, swap out CB's custom LongHashMap with Long2ObjectOpenHashMap

These collections are super fast as seen
http://java-performance.info/hashmap-overview-jdk-fastutil-goldman-sachs-hppc-koloboke-trove-january-2015/

Spigot-API-Patches/0002-Add-minimal-fastutil-int-long-based-collections.patch

@@ -1,8 +1,10 @@
-From 8856eed99403409f9904fb8315ff4f2e95065239 Mon Sep 17 00:00:00 2001
+From bc17a29787a7d9c927d9812b74db623b9ca066b2 Mon Sep 17 00:00:00 2001
 From: Aikar <aikar@aikar.co>
 Date: Mon, 21 Mar 2016 18:17:14 -0400
-Subject: [PATCH] Add minimal fastutil int based collections
+Subject: [PATCH] Add minimal fastutil int/long based collections
 
+Importing entire FastUtil library would be massive. Just import minimal useful ones
+we might actually use.
 
 diff --git a/src/main/java/it/unimi/dsi/fastutil/AbstractIndirectDoublePriorityQueue.java b/src/main/java/it/unimi/dsi/fastutil/AbstractIndirectDoublePriorityQueue.java
 new file mode 100644

Spigot-Server-Patches/0124-Use-FastUtil-Long-Int-HashMap-s.patch

@@ -0,0 +1,56 @@
+From 7f072c4fec3c43714ecadef5b6931f789bf4f648 Mon Sep 17 00:00:00 2001
+From: Aikar <aikar@aikar.co>
+Date: Wed, 30 Mar 2016 02:13:24 -0400
+Subject: [PATCH] Use FastUtil Long/Int HashMap's
+
+For DataWatcher, swap out plain Integer key HashMap for a Int2ObjectOpenHashMap
+For ChunkProviderServer, swap out CB's custom LongHashMap with Long2ObjectOpenHashMap
+
+These collections are super fast as seen
+http://java-performance.info/hashmap-overview-jdk-fastutil-goldman-sachs-hppc-koloboke-trove-january-2015/
+
+diff --git a/src/main/java/net/minecraft/server/ChunkProviderServer.java b/src/main/java/net/minecraft/server/ChunkProviderServer.java
+index f31ffe2..646197c 100644
+--- a/src/main/java/net/minecraft/server/ChunkProviderServer.java
++++ b/src/main/java/net/minecraft/server/ChunkProviderServer.java
+@@ -5,6 +5,7 @@ import java.util.Iterator;
+ import java.util.List;
+ 
+ import com.destroystokyo.paper.exception.ServerInternalException;
++import it.unimi.dsi.fastutil.longs.Long2ObjectOpenHashMap; // Paper
+ import org.apache.logging.log4j.LogManager;
+ import org.apache.logging.log4j.Logger;
+ 
+@@ -26,7 +27,7 @@ public class ChunkProviderServer implements IChunkProvider {
+     private final IChunkLoader chunkLoader;
+     // Paper start
+     protected Chunk lastChunkByPos = null;
+-    public LongObjectHashMap<Chunk> chunks = new LongObjectHashMap<Chunk>() {
++    public Long2ObjectOpenHashMap<Chunk> chunks = new Long2ObjectOpenHashMap<Chunk>() {
+         @Override
+         public Chunk get(long key) {
+             if (lastChunkByPos != null && key == lastChunkByPos.chunkKey) {
+diff --git a/src/main/java/net/minecraft/server/DataWatcher.java b/src/main/java/net/minecraft/server/DataWatcher.java
+index 26bec1c..88f340d 100644
+--- a/src/main/java/net/minecraft/server/DataWatcher.java
++++ b/src/main/java/net/minecraft/server/DataWatcher.java
+@@ -11,13 +11,15 @@ import java.util.List;
+ import java.util.Map;
+ import java.util.concurrent.locks.ReadWriteLock;
+ import java.util.concurrent.locks.ReentrantReadWriteLock;
++
++import it.unimi.dsi.fastutil.ints.Int2ObjectOpenHashMap; // Paper
+ import org.apache.commons.lang3.ObjectUtils;
+ 
+ public class DataWatcher {
+ 
+     private static final Map<Class<? extends Entity>, Integer> a = Maps.newHashMap();
+     private final Entity b;
+-    private final Map<Integer, DataWatcher.Item<?>> c = Maps.newHashMap();
++    private final Map<Integer, DataWatcher.Item<?>> c = new Int2ObjectOpenHashMap<>(); // Paper
+     private final ReadWriteLock d = new ReentrantReadWriteLock();
+     private boolean e = true;
+     private boolean f;
+-- 
+2.7.4
+