diff --git a/src/main/java/org/dimdev/jeid/mixin/core/misc/MixinStatList.java b/src/main/java/org/dimdev/jeid/mixin/core/misc/MixinStatList.java
index 4700e41..7be72bc 100644
--- a/src/main/java/org/dimdev/jeid/mixin/core/misc/MixinStatList.java
+++ b/src/main/java/org/dimdev/jeid/mixin/core/misc/MixinStatList.java
@@ -1,6 +1,8 @@
 package org.dimdev.jeid.mixin.core.misc;
 
 import com.llamalad7.mixinextras.sugar.Local;
+import it.unimi.dsi.fastutil.objects.ObjectOpenHashSet;
+import it.unimi.dsi.fastutil.objects.Reference2ObjectOpenHashMap;
 import net.minecraft.block.Block;
 import net.minecraft.init.Blocks;
 import net.minecraft.item.Item;
@@ -23,10 +25,9 @@
 import org.spongepowered.asm.mixin.injection.callback.CallbackInfoReturnable;
 
 import java.util.ArrayList;
-import java.util.HashMap;
-import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
+import java.util.Set;
 
 /**
  * Rewrite most of the class to support an unlimited number of IDs (map rather than array).
@@ -63,17 +64,17 @@ public final class MixinStatList {
     @Shadow
     private static StatBase[] OBJECTS_DROPPED_STATS;
     @Unique
-    private static final Map<Block, StatBase> BLOCKS_STATS_MAP = new HashMap<>();
+    private static final Map<Block, StatBase> BLOCKS_STATS_MAP = new Reference2ObjectOpenHashMap<>();
     @Unique
-    private static final Map<Item, StatBase> CRAFTS_STATS_MAP = new HashMap<>();
+    private static final Map<Item, StatBase> CRAFTS_STATS_MAP = new Reference2ObjectOpenHashMap<>();
     @Unique
-    private static final Map<Item, StatBase> OBJECT_USE_STATS_MAP = new HashMap<>();
+    private static final Map<Item, StatBase> OBJECT_USE_STATS_MAP = new Reference2ObjectOpenHashMap<>();
     @Unique
-    private static final Map<Item, StatBase> OBJECT_BREAK_STATS_MAP = new HashMap<>();
+    private static final Map<Item, StatBase> OBJECT_BREAK_STATS_MAP = new Reference2ObjectOpenHashMap<>();
     @Unique
-    private static final Map<Item, StatBase> OBJECTS_PICKED_UP_STATS_MAP = new HashMap<>();
+    private static final Map<Item, StatBase> OBJECTS_PICKED_UP_STATS_MAP = new Reference2ObjectOpenHashMap<>();
     @Unique
-    private static final Map<Item, StatBase> OBJECTS_DROPPED_STATS_MAP = new HashMap<>();
+    private static final Map<Item, StatBase> OBJECTS_DROPPED_STATS_MAP = new Reference2ObjectOpenHashMap<>();
 
     /**
      * @reason Reduce memory footprint of stat arrays
@@ -364,7 +365,7 @@ public final class MixinStatList {
         int requiredCapacity = BLOCKS_STATS_MAP.size() + CRAFTS_STATS_MAP.size()
                 + OBJECT_USE_STATS_MAP.size() + OBJECT_BREAK_STATS_MAP.size()
                 + OBJECTS_PICKED_UP_STATS_MAP.size() + OBJECTS_DROPPED_STATS_MAP.size();
-        HashSet<StatBase> knownStats = new HashSet<>((int) Math.ceil(requiredCapacity / 0.75f));
+        Set<StatBase> knownStats = new ObjectOpenHashSet<>(requiredCapacity + 1);
         knownStats.addAll(BLOCKS_STATS_MAP.values());
         knownStats.addAll(CRAFTS_STATS_MAP.values());
         knownStats.addAll(OBJECT_USE_STATS_MAP.values());
diff --git a/src/main/java/org/dimdev/jeid/mixin/core/world/MixinBlockStateContainer.java b/src/main/java/org/dimdev/jeid/mixin/core/world/MixinBlockStateContainer.java
index d7a225a..6fefc8e 100644
--- a/src/main/java/org/dimdev/jeid/mixin/core/world/MixinBlockStateContainer.java
+++ b/src/main/java/org/dimdev/jeid/mixin/core/world/MixinBlockStateContainer.java
@@ -1,5 +1,7 @@
 package org.dimdev.jeid.mixin.core.world;
 
+import it.unimi.dsi.fastutil.objects.Reference2IntMap;
+import it.unimi.dsi.fastutil.objects.Reference2IntOpenHashMap;
 import net.minecraft.block.Block;
 import net.minecraft.block.state.IBlockState;
 import net.minecraft.init.Blocks;
@@ -14,9 +16,6 @@
 import org.spongepowered.asm.mixin.injection.callback.CallbackInfo;
 import org.spongepowered.asm.mixin.injection.callback.CallbackInfoReturnable;
 
-import java.util.HashMap;
-import java.util.Map;
-
 @Mixin(BlockStateContainer.class)
 public abstract class MixinBlockStateContainer implements INewBlockStateContainer {
     @Unique
@@ -53,13 +52,14 @@ public void setLegacyAdd2(NibbleArray add2) {
     @SuppressWarnings("deprecation")
     @Inject(method = "getDataForNBT", at = @At("HEAD"), cancellable = true)
     private void reid$newGetDataForNBT(byte[] blockIds, NibbleArray data, CallbackInfoReturnable<NibbleArray> cir) {
-        HashMap<IBlockState, Integer> stateIDMap = new HashMap<>();
+        Reference2IntMap<IBlockState> stateIDMap = new Reference2IntOpenHashMap<>();
         int nextID = 0;
         for (int index = 0; index < 4096; ++index) {
             IBlockState state = get(index);
-            Integer paletteID = stateIDMap.get(state);
-            if (paletteID == null) {
-                paletteID = nextID++;
+            int paletteID = stateIDMap.getOrDefault(state, -1);
+            if (paletteID == -1) {
+                paletteID = nextID;
+                ++nextID;
                 stateIDMap.put(state, paletteID);
             }
 
@@ -72,8 +72,8 @@ public void setLegacyAdd2(NibbleArray add2) {
         }
 
         temporaryPalette = new int[nextID];
-        for (Map.Entry<IBlockState, Integer> entry : stateIDMap.entrySet()) {
-            temporaryPalette[entry.getValue()] = Block.BLOCK_STATE_IDS.get(entry.getKey());
+        for (final Reference2IntMap.Entry<IBlockState> entry : stateIDMap.reference2IntEntrySet()) {
+            temporaryPalette[entry.getIntValue()] = Block.BLOCK_STATE_IDS.get(entry.getKey());
         }
 
         cir.setReturnValue(null);