diff --git a/pom.xml b/pom.xml
index a53f06917..4c86a507e 100644
--- a/pom.xml
+++ b/pom.xml
@@ -155,9 +155,9 @@
 	</repositories>
 	<dependencies>
 		<dependency>
-			<groupId>com.github.Querz</groupId>
-			<artifactId>NBT</artifactId>
-			<version>5.5</version>
+			<groupId>io.timeandspace</groupId>
+			<artifactId>smoothie-map</artifactId>
+			<version>2.0.2</version>
 		</dependency>
 		<!-- Spigot API -->
 		<dependency>
diff --git a/src/main/java/com/volmit/iris/scaffold/engine/DirectWorldWriter.java b/src/main/java/com/volmit/iris/scaffold/engine/DirectWorldWriter.java
index c0e7cb2d9..7e1d16ff7 100644
--- a/src/main/java/com/volmit/iris/scaffold/engine/DirectWorldWriter.java
+++ b/src/main/java/com/volmit/iris/scaffold/engine/DirectWorldWriter.java
@@ -5,9 +5,7 @@ import com.volmit.iris.nms.INMS;
 import com.volmit.iris.scaffold.cache.Cache;
 import com.volmit.iris.scaffold.parallel.BurstExecutor;
 import com.volmit.iris.scaffold.parallel.MultiBurst;
-import com.volmit.iris.util.B;
-import com.volmit.iris.util.KList;
-import com.volmit.iris.util.KMap;
+import com.volmit.iris.util.*;
 import net.querz.mca.Chunk;
 import net.querz.mca.MCAFile;
 import net.querz.mca.MCAUtil;
@@ -24,41 +22,64 @@ import java.io.IOException;
 public class DirectWorldWriter {
     private final File worldFolder;
     private final KMap<Long, MCAFile> writeBuffer;
+    private final KMap<Long, Long> lastUse;
+    private static final KMap<String, CompoundTag> blockDataCache = new KMap<>();
+    private static final KMap<Biome, Integer> biomeIds = computeBiomeIDs();
 
     public DirectWorldWriter(File worldFolder)
     {
         this.worldFolder = worldFolder;
+        lastUse = new KMap<>();
         writeBuffer = new KMap<>();
         new File(worldFolder, "region").mkdirs();
     }
 
     public void flush()
     {
-        BurstExecutor ex = MultiBurst.burst.burst(writeBuffer.size());
-        writeBuffer.v().forEach((i) -> ex.queue(i::cleanupPalettesAndBlockStates));
-        ex.complete();
         BurstExecutor ex2 = MultiBurst.burst.burst(writeBuffer.size());
 
         for(Long i : writeBuffer.k())
         {
-            int x = Cache.keyX(i);
-            int z = Cache.keyZ(i);
-            try {
-                File f = getMCAFile(x, z);
-
-                if(!f.exists())
-                {
-                    f.getParentFile().mkdirs();
-                    f.createNewFile();
-                }
-
-                MCAUtil.write(writeBuffer.get(i), f, true);
-            } catch (Throwable e) {
-                e.printStackTrace();
+            if(M.ms() - lastUse.get(i) < 15000)
+            {
+                continue;
             }
-        }
 
-        writeBuffer.clear();
+            ex2.queue(() -> {
+                int x = Cache.keyX(i);
+                int z = Cache.keyZ(i);
+                try {
+                    File f = getMCAFile(x, z);
+
+                    if(!f.exists())
+                    {
+                        f.getParentFile().mkdirs();
+                        f.createNewFile();
+                    }
+
+                    try
+                    {
+                        writeBuffer.get(i).cleanupPalettesAndBlockStates();
+                    }
+
+                    catch(Throwable e)
+                    {
+
+                    }
+
+                    lastUse.remove(i);
+                    MCAUtil.write(writeBuffer.get(i), f, true);
+                    writeBuffer.remove(i);
+                } catch (Throwable e) {
+                    e.printStackTrace();
+                }
+            });
+        }
+    }
+
+    public void optimizeChunk(int x, int z)
+    {
+        getChunk(x, z).cleanupPalettesAndBlockStates();
     }
 
     public File getMCAFile(int x, int z)
@@ -66,8 +87,12 @@ public class DirectWorldWriter {
         return new File(worldFolder, "region/r." + x + "." + z + ".mca");
     }
 
-    public BlockData getBlockData(CompoundTag tag)
-    {
+    public BlockData getBlockData(CompoundTag tag) {
+        if (tag == null)
+        {
+            return B.getAir();
+        }
+
         String p = tag.getString("Name");
 
         if(tag.containsKey("Properties"))
@@ -84,16 +109,29 @@ public class DirectWorldWriter {
             p += m.toString(",") + "]";
         }
 
-        return B.get(p);
+        BlockData b = B.getOrNull(p);
+
+        if(b == null)
+        {
+            return B.getAir();
+        }
+
+        return b;
     }
 
     public CompoundTag getCompound(BlockData blockData)
     {
+        String data = blockData.getAsString(true);
+
+        if(blockDataCache.containsKey(data))
+        {
+            return blockDataCache.get(data).clone();
+        }
+
         CompoundTag s = new CompoundTag();
         NamespacedKey key = blockData.getMaterial().getKey();
         s.putString("Name", key.getNamespace() + ":" + key.getKey());
 
-        String data = blockData.getAsString(true);
 
         if(data.contains("["))
         {
@@ -120,6 +158,7 @@ public class DirectWorldWriter {
             s.put("Properties", props);
         }
 
+        blockDataCache.put(data, s.clone());
         return s;
     }
 
@@ -151,7 +190,7 @@ public class DirectWorldWriter {
 
     public void setBiome(int x, int y, int z, Biome biome)
     {
-        getChunk(x>>4, z>>4).setBiomeAt(x&15, y, z &15, INMS.get().getBiomeId(biome));
+        getChunk(x>>4, z>>4).setBiomeAt(x&15, y, z &15, biomeIds.get(biome));
     }
 
     public Section getChunkSection(int x, int y, int z)
@@ -176,6 +215,7 @@ public class DirectWorldWriter {
         if(c == null)
         {
             c = Chunk.newChunk();
+            lastUse.put(Cache.key(x >> 5, z >> 5), M.ms());
             mca.setChunk(x&31, z&31, c);
         }
 
@@ -204,7 +244,23 @@ public class DirectWorldWriter {
             }
         }
 
+        lastUse.put(key, M.ms());
         writeBuffer.put(key, mca);
         return mca;
     }
+
+    public int size() {
+        return writeBuffer.size();
+    }
+
+    private static KMap<Biome, Integer> computeBiomeIDs() {
+        KMap<Biome, Integer> biomeIds = new KMap<>();
+
+        for(Biome i : Biome.values())
+        {
+            biomeIds.put(i, INMS.get().getBiomeId(i));
+        }
+
+        return biomeIds;
+    }
 }
diff --git a/src/main/java/com/volmit/iris/scaffold/engine/EngineCompositeGenerator.java b/src/main/java/com/volmit/iris/scaffold/engine/EngineCompositeGenerator.java
index 1b7bd5fb8..0185b5b4d 100644
--- a/src/main/java/com/volmit/iris/scaffold/engine/EngineCompositeGenerator.java
+++ b/src/main/java/com/volmit/iris/scaffold/engine/EngineCompositeGenerator.java
@@ -338,6 +338,7 @@ public class EngineCompositeGenerator extends ChunkGenerator implements IrisAcce
     {
         int ox = x << 4;
         int oz = z << 4;
+        net.querz.mca.Chunk cc = writer.getChunk(x, z);
         generateChunkRawData(w, x, z, new TerrainChunk() {
             @Override
             public void setRaw(ChunkData data) {
@@ -356,12 +357,12 @@ public class EngineCompositeGenerator extends ChunkGenerator implements IrisAcce
 
             @Override
             public void setBiome(int x, int z, Biome bio) {
-                writer.setBiome(ox + x, 0, oz + z, bio);
+                setBiome(ox + x, 0, oz + z, bio);
             }
 
             @Override
             public void setBiome(int x, int y, int z, Biome bio) {
-                writer.setBiome(ox + x, y, oz + z, bio);
+                writer.setBiome((ox + x), y, oz + z, bio);
             }
 
             @Override
@@ -371,12 +372,22 @@ public class EngineCompositeGenerator extends ChunkGenerator implements IrisAcce
 
             @Override
             public void setBlock(int x, int y, int z, BlockData blockData) {
-                writer.setBlockData(x+ox, y, z+oz, blockData);
+                cc.setBlockStateAt((x+ox)&15, y, (z+oz)&15, writer.getCompound(blockData), false);
             }
 
             @Override
             public BlockData getBlockData(int x, int y, int z) {
-                return writer.getBlockData(x + ox, y, z + oz);
+                if(y > getMaxHeight())
+                {
+                    y = getMaxHeight();
+                }
+
+                if(y < 0)
+                {
+                    y = 0;
+                }
+
+                return writer.getBlockData(cc.getBlockStateAt((x+ox)&15, y, (z+oz)&15));
             }
 
             @Override
@@ -431,6 +442,7 @@ public class EngineCompositeGenerator extends ChunkGenerator implements IrisAcce
                 return 0;
             }
         }).run();
+        writer.optimizeChunk(x, z);
     }
 
     public Chunk generatePaper(World world, int x, int z)
diff --git a/src/main/java/com/volmit/iris/util/PregenJob.java b/src/main/java/com/volmit/iris/util/PregenJob.java
index e7db8f98e..abe876c8e 100644
--- a/src/main/java/com/volmit/iris/util/PregenJob.java
+++ b/src/main/java/com/volmit/iris/util/PregenJob.java
@@ -147,6 +147,7 @@ public class PregenJob implements Listener
 	{
 		try
 		{
+			instance.writer.flush();
 			Bukkit.getScheduler().cancelTask(task);
 
 			if(consumer != null)
@@ -172,6 +173,7 @@ public class PregenJob implements Listener
 		instance.pms = instance.s.getMilliseconds();
 		instance.paused = true;
 		instance.pausedAt = M.ms();
+		instance.writer.flush();
 	}
 
 	public static void resume()
@@ -207,6 +209,8 @@ public class PregenJob implements Listener
 			tick(skip);
 		}
 
+		Iris.warn("Size: " + writer.size());
+
 		PrecisionStopwatch p = PrecisionStopwatch.start();
 
 		if(PaperLib.isPaper())
diff --git a/src/main/java/net/querz/mca/Chunk.java b/src/main/java/net/querz/mca/Chunk.java
index d305df04d..0236717f2 100644
--- a/src/main/java/net/querz/mca/Chunk.java
+++ b/src/main/java/net/querz/mca/Chunk.java
@@ -30,7 +30,7 @@ public class Chunk {
 	private int[] biomes;
 	private CompoundTag heightMaps;
 	private CompoundTag carvingMasks;
-	private Section[] sections = new Section[16]; //always initialized with size = 16 for fast access
+	private final Section[] sections = new Section[16];
 	private ListTag<CompoundTag> entities;
 	private ListTag<CompoundTag> tileEntities;
 	private ListTag<CompoundTag> tileTicks;
diff --git a/src/main/java/net/querz/mca/MCAFile.java b/src/main/java/net/querz/mca/MCAFile.java
index 920372244..73eda6075 100644
--- a/src/main/java/net/querz/mca/MCAFile.java
+++ b/src/main/java/net/querz/mca/MCAFile.java
@@ -63,6 +63,11 @@ public class MCAFile {
 		}
 	}
 
+	public Chunk[] getChunks()
+	{
+		return chunks;
+	}
+
 	/**
 	 * Calls {@link MCAFile#serialize(RandomAccessFile, boolean)} without updating any timestamps.
 	 * @see MCAFile#serialize(RandomAccessFile, boolean)
diff --git a/src/main/java/net/querz/mca/Section.java b/src/main/java/net/querz/mca/Section.java
index 312035a39..51851d4de 100644
--- a/src/main/java/net/querz/mca/Section.java
+++ b/src/main/java/net/querz/mca/Section.java
@@ -1,19 +1,24 @@
 package net.querz.mca;
 
-import static net.querz.mca.LoadFlags.*;
+import io.timeandspace.smoothie.OptimizationObjective;
+import io.timeandspace.smoothie.SmoothieMap;
 import net.querz.nbt.tag.ByteArrayTag;
 import net.querz.nbt.tag.CompoundTag;
 import net.querz.nbt.tag.ListTag;
 import net.querz.nbt.tag.LongArrayTag;
+
 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 
+import static net.querz.mca.LoadFlags.*;
+
 public class Section {
 
 	private CompoundTag data;
-	private Map<String, List<PaletteIndex>> valueIndexedPalette = new HashMap<>();
+	private Map<String, List<PaletteIndex>> valueIndexedPalette = SmoothieMap.<String, List<PaletteIndex>>newBuilder()
+			.optimizeFor(OptimizationObjective.FOOTPRINT).build();
 	private ListTag<CompoundTag> palette;
 	private byte[] blockLight;
 	private long[] blockStates;
diff --git a/src/main/java/net/querz/nbt/tag/CompoundTag.java b/src/main/java/net/querz/nbt/tag/CompoundTag.java
index 3909a72c1..eb8d35217 100644
--- a/src/main/java/net/querz/nbt/tag/CompoundTag.java
+++ b/src/main/java/net/querz/nbt/tag/CompoundTag.java
@@ -1,13 +1,9 @@
 package net.querz.nbt.tag;
 
+import com.volmit.iris.util.KMap;
 import net.querz.io.MaxDepthIO;
 
-import java.util.Collection;
-import java.util.HashMap;
-import java.util.Iterator;
-import java.util.Map;
-import java.util.Objects;
-import java.util.Set;
+import java.util.*;
 import java.util.function.BiConsumer;
 
 public class CompoundTag extends Tag<Map<String, Tag<?>>> implements Iterable<Map.Entry<String, Tag<?>>>, Comparable<CompoundTag>, MaxDepthIO {
@@ -24,7 +20,7 @@ public class CompoundTag extends Tag<Map<String, Tag<?>>> implements Iterable<Ma
 	}
 
 	private static Map<String, Tag<?>> createEmptyValue() {
-		return new HashMap<>(8);
+		return new KMap<>();
 	}
 
 	public int size() {
diff --git a/src/main/java/net/querz/nbt/tag/ListTag.java b/src/main/java/net/querz/nbt/tag/ListTag.java
index 008e3aaa3..a72b94b51 100644
--- a/src/main/java/net/querz/nbt/tag/ListTag.java
+++ b/src/main/java/net/querz/nbt/tag/ListTag.java
@@ -1,13 +1,9 @@
 package net.querz.nbt.tag;
 
+import com.volmit.iris.util.KList;
 import net.querz.io.MaxDepthIO;
 
-import java.util.ArrayList;
-import java.util.Collection;
-import java.util.Comparator;
-import java.util.Iterator;
-import java.util.List;
-import java.util.Objects;
+import java.util.*;
 import java.util.function.Consumer;
 
 /**
@@ -52,10 +48,10 @@ public class ListTag<T extends Tag<?>> extends Tag<List<T>> implements Iterable<
 	 *
 	 * @param <T> Type of the list elements
 	 * @param initialCapacity The initial capacity of the returned List
-	 * @return An instance of {@link java.util.List} with an initial capacity of 3
+	 * @return An instance of {@link List} with an initial capacity of 3
 	 * */
 	private static <T> List<T> createEmptyValue(int initialCapacity) {
-		return new ArrayList<>(initialCapacity);
+		return new KList<>(initialCapacity);
 	}
 
 	/**