diff --git a/src/main/java/net/minecraftforge/registries/ForgeRegistry.java b/src/main/java/net/minecraftforge/registries/ForgeRegistry.java
index b0c53982dc..f18ac54bcb 100644
--- a/src/main/java/net/minecraftforge/registries/ForgeRegistry.java
+++ b/src/main/java/net/minecraftforge/registries/ForgeRegistry.java
@@ -11,7 +11,6 @@ import java.util.Collection;
 import java.util.Collections;
 import java.util.Comparator;
 import java.util.HashMap;
-import java.util.HashSet;
 import java.util.Iterator;
 import java.util.List;
 import java.util.Locale;
@@ -20,12 +19,16 @@ import java.util.Map.Entry;
 import java.util.Optional;
 import java.util.Set;
 import java.util.TreeMap;
-import java.util.TreeSet;
 
 import com.mojang.datafixers.util.Pair;
 import com.mojang.serialization.Codec;
 import com.mojang.serialization.DataResult;
 import com.mojang.serialization.DynamicOps;
+import it.unimi.dsi.fastutil.ints.IntOpenHashSet;
+import it.unimi.dsi.fastutil.ints.IntRBTreeSet;
+import it.unimi.dsi.fastutil.ints.IntSet;
+import it.unimi.dsi.fastutil.objects.Object2IntMap;
+import it.unimi.dsi.fastutil.objects.Object2IntRBTreeMap;
 import net.minecraft.core.Holder;
 import net.minecraft.core.HolderSet;
 import net.minecraft.tags.TagKey;
@@ -56,9 +59,12 @@ import org.jetbrains.annotations.ApiStatus;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
+/**
+ * Internal - use the public {@link IForgeRegistry} and {@link ForgeRegistries} APIs to get the data
+ */
 @ApiStatus.Internal
 public class ForgeRegistry<V> implements IForgeRegistryInternal<V>, IForgeRegistryModifiable<V> {
-    public static Marker REGISTRIES = MarkerManager.getMarker("REGISTRIES");
+    public static final Marker REGISTRIES = MarkerManager.getMarker("REGISTRIES");
     private static final Marker REGISTRYDUMP = MarkerManager.getMarker("REGISTRYDUMP");
     private static final Logger LOGGER = LogManager.getLogger();
     private final RegistryManager stage;
@@ -76,7 +82,7 @@ public class ForgeRegistry<V> implements IForgeRegistryInternal<V>, IForgeRegist
     private final BakeCallback<V> bake;
     private final MissingFactory<V> missing;
     private final BitSet availabilityMap;
-    private final Set<Integer> blocked = new HashSet<>();
+    private final IntSet blocked = new IntOpenHashSet();
     private final Multimap<ResourceLocation, V> overrides = ArrayListMultimap.create();
     private final Map<ResourceLocation, Holder.Reference<V>> delegatesByName = new HashMap<>();
     private final Map<V, Holder.Reference<V>> delegatesByValue = new HashMap<>();
@@ -708,12 +714,12 @@ public class ForgeRegistry<V> implements IForgeRegistryInternal<V>, IForgeRegist
 
     private record DumpRow(String id, String key, String value) {}
 
-    public void loadIds(Map<ResourceLocation, Integer> ids, Map<ResourceLocation, String> overrides, Map<ResourceLocation, Integer> missing, Map<ResourceLocation, IdMappingEvent.IdRemapping> remapped, ForgeRegistry<V> old, ResourceLocation name) {
+    public void loadIds(Object2IntMap<ResourceLocation> ids, Map<ResourceLocation, String> overrides, Object2IntMap<ResourceLocation> missing, Map<ResourceLocation, IdMappingEvent.IdRemapping> remapped, ForgeRegistry<V> old, ResourceLocation name) {
         Map<ResourceLocation, String> ovs = new HashMap<>(overrides);
-        for (Map.Entry<ResourceLocation, Integer> entry : ids.entrySet()) {
+        for (Object2IntMap.Entry<ResourceLocation> entry : ids.object2IntEntrySet()) {
             ResourceLocation itemName = entry.getKey();
 
-            int newId = entry.getValue();
+            int newId = entry.getIntValue();
             int currId = old.getIDRaw(itemName);
 
             if (currId == -1) {
@@ -832,10 +838,10 @@ public class ForgeRegistry<V> implements IForgeRegistryInternal<V>, IForgeRegist
     }
 
     public static class Snapshot {
-        private static final Comparator<ResourceLocation> sorter = (a,b) -> a.compareNamespaced(b);
-        public final Map<ResourceLocation, Integer> ids = new TreeMap<>(sorter);
+        private static final Comparator<ResourceLocation> sorter = ResourceLocation::compareNamespaced;
+        public final Object2IntMap<ResourceLocation> ids = new Object2IntRBTreeMap<>(sorter);
         public final Map<ResourceLocation, ResourceLocation> aliases = new TreeMap<>(sorter);
-        public final Set<Integer> blocked = new TreeSet<>();
+        public final IntSet blocked = new IntRBTreeSet();
         public final Map<ResourceLocation, String> overrides = new TreeMap<>(sorter);
         private FriendlyByteBuf binary = null;
 
@@ -843,16 +849,16 @@ public class ForgeRegistry<V> implements IForgeRegistryInternal<V>, IForgeRegist
             CompoundTag data = new CompoundTag();
 
             ListTag ids = new ListTag();
-            this.ids.entrySet().stream().forEach(e -> {
+            this.ids.object2IntEntrySet().forEach(e -> {
                 CompoundTag tag = new CompoundTag();
                 tag.putString("K", e.getKey().toString());
-                tag.putInt("V", e.getValue());
+                tag.putInt("V", e.getIntValue());
                 ids.add(tag);
             });
             data.put("ids", ids);
 
             ListTag aliases = new ListTag();
-            this.aliases.entrySet().stream().forEach(e -> {
+            this.aliases.entrySet().forEach(e -> {
                 CompoundTag tag = new CompoundTag();
                 tag.putString("K", e.getKey().toString());
                 tag.putString("V", e.getValue().toString());
@@ -861,7 +867,7 @@ public class ForgeRegistry<V> implements IForgeRegistryInternal<V>, IForgeRegist
             data.put("aliases", aliases);
 
             ListTag overrides = new ListTag();
-            this.overrides.entrySet().stream().forEach(e -> {
+            this.overrides.entrySet().forEach(e -> {
                 CompoundTag tag = new CompoundTag();
                 tag.putString("K", e.getKey().toString());
                 tag.putString("V", e.getValue());
@@ -869,7 +875,7 @@ public class ForgeRegistry<V> implements IForgeRegistryInternal<V>, IForgeRegist
             });
             data.put("overrides", overrides);
 
-            int[] blocked = this.blocked.stream().mapToInt(x->x).sorted().toArray();
+            int[] blocked = this.blocked.intStream().sorted().toArray();
             data.putIntArray("blocked", blocked);
 
             return data;
@@ -932,14 +938,14 @@ public class ForgeRegistry<V> implements IForgeRegistryInternal<V>, IForgeRegist
     }
 
     @SuppressWarnings("unchecked")
-    public MissingMappingsEvent getMissingEvent(ResourceLocation name, Map<ResourceLocation, Integer> map) {
+    public MissingMappingsEvent getMissingEvent(ResourceLocation name, Object2IntMap<ResourceLocation> map) {
         List<MissingMappingsEvent.Mapping<V>> lst = new ArrayList<>();
         ForgeRegistry<V> pool = RegistryManager.ACTIVE.getRegistry(name);
-        map.forEach((rl, id) -> lst.add(new MissingMappingsEvent.Mapping<>(this, pool, rl, id)));
+        map.object2IntEntrySet().forEach(entry -> lst.add(new MissingMappingsEvent.Mapping<>(this, pool, entry.getKey(), entry.getIntValue())));
         return new MissingMappingsEvent(ResourceKey.createRegistryKey(name), this, (Collection<MissingMappingsEvent.Mapping<?>>) (Collection<?>) lst);
     }
 
-    void processMissingEvent(ResourceLocation name, ForgeRegistry<V> pool, List<MissingMappingsEvent.Mapping<V>> mappings, Map<ResourceLocation, Integer> missing, Map<ResourceLocation, IdMappingEvent.IdRemapping> remaps, Collection<ResourceLocation> defaulted, Collection<ResourceLocation> failed, boolean injectNetworkDummies) {
+    void processMissingEvent(ResourceLocation name, ForgeRegistry<V> pool, List<MissingMappingsEvent.Mapping<V>> mappings, Object2IntMap<ResourceLocation> missing, Map<ResourceLocation, IdMappingEvent.IdRemapping> remaps, Collection<ResourceLocation> defaulted, Collection<ResourceLocation> failed, boolean injectNetworkDummies) {
         LOGGER.debug(REGISTRIES,"Processing missing event for {}:", name);
         int ignored = 0;
 
@@ -952,7 +958,7 @@ public class ForgeRegistry<V> implements IForgeRegistryInternal<V>, IForgeRegist
                 ResourceLocation newName = pool.getKey(remap.target);
                 LOGGER.debug(REGISTRIES,"  Remapping {} -> {}.", remap.key, newName);
 
-                missing.remove(remap.key);
+                missing.removeInt(remap.key);
                 //I don't think this will work, but I dont think it ever worked.. the item is already in the map with a different id... we want to fix that..
                 int realId = this.add(remap.id, newName, remap.target);
                 if (realId != remap.id)
diff --git a/src/main/java/net/minecraftforge/registries/GameData.java b/src/main/java/net/minecraftforge/registries/GameData.java
index c564bdf9af..c58fcc8085 100644
--- a/src/main/java/net/minecraftforge/registries/GameData.java
+++ b/src/main/java/net/minecraftforge/registries/GameData.java
@@ -7,7 +7,6 @@ package net.minecraftforge.registries;
 
 import com.google.common.collect.ArrayListMultimap;
 import com.google.common.collect.ImmutableMap;
-import com.google.common.collect.Maps;
 import com.google.common.collect.Multimap;
 import com.mojang.serialization.Codec;
 import com.mojang.serialization.Lifecycle;
@@ -23,6 +22,9 @@ import java.util.Map;
 import java.util.Set;
 import java.util.function.BiConsumer;
 import java.util.stream.Collectors;
+
+import it.unimi.dsi.fastutil.objects.Object2IntLinkedOpenHashMap;
+import it.unimi.dsi.fastutil.objects.Object2IntMap;
 import net.minecraft.core.IdMapper;
 import net.minecraft.core.MappedRegistry;
 import net.minecraft.core.Registry;
@@ -69,12 +71,13 @@ import org.jetbrains.annotations.Nullable;
 /**
  * INTERNAL ONLY
  * MODDERS SHOULD HAVE NO REASON TO USE THIS CLASS
+ * <p>Use the public {@link IForgeRegistry} and {@link ForgeRegistries} APIs to get the data</p>
  */
 @ApiStatus.Internal
 public class GameData
 {
     private static final Logger LOGGER = LogManager.getLogger();
-    private static Marker REGISTRIES = ForgeRegistry.REGISTRIES;
+    private static final Marker REGISTRIES = ForgeRegistry.REGISTRIES;
     private static final int MAX_VARINT = Integer.MAX_VALUE - 1; //We were told it is their intention to have everything in a reg be unlimited, so assume that until we find cases where it isnt.
 
     private static final ResourceLocation BLOCK_TO_ITEM = new ResourceLocation("minecraft:blocktoitemmap");
@@ -368,10 +371,9 @@ public class GameData
         @SuppressWarnings("unused")
         void remove(I key)
         {
-            @SuppressWarnings("deprecation")
-            Integer prev = this.tToId.remove(key);
-            if (prev != null)
-            {
+            boolean hadId = this.tToId.containsKey(key);
+            int prev = this.tToId.removeInt(key);
+            if (hadId) {
                 this.idToT.set(prev, null);
             }
         }
@@ -421,22 +423,17 @@ public class GameData
         @Override
         public void onCreate(IForgeRegistryInternal<Block> owner, RegistryManager stage)
         {
-            final ClearableObjectIntIdentityMap<BlockState> idMap = new ClearableObjectIntIdentityMap<BlockState>()
+            final ClearableObjectIntIdentityMap<BlockState> idMap = new ClearableObjectIntIdentityMap<>()
             {
                 @SuppressWarnings("deprecation")
                 @Override
                 public int getId(BlockState key)
                 {
-                    Integer integer = (Integer)this.tToId.get(key);
-                    // There are some cases where this map is queried to serialize a state that is valid,
-                    //but somehow not in this list, so attempt to get real metadata. Doing this hear saves us 7 patches
-                    //if (integer == null && key != null)
-                    //    integer = this.identityMap.get(key.getBlock().getStateFromMeta(key.getBlock().getMetaFromState(key)));
-                    return integer == null ? -1 : integer.intValue();
+                    return this.tToId.containsKey(key) ? this.tToId.getInt(key) : -1;
                 }
             };
             owner.setSlaveMap(BLOCKSTATE_TO_ID, idMap);
-            owner.setSlaveMap(BLOCK_TO_ITEM, Maps.newHashMap());
+            owner.setSlaveMap(BLOCK_TO_ITEM, new HashMap<>());
         }
 
         @Override
@@ -597,11 +594,11 @@ public class GameData
 
         if (isLocalWorld)
         {
-            List<ResourceLocation> missingRegs = snapshot.keySet().stream().filter(name -> !RegistryManager.ACTIVE.registries.containsKey(name)).collect(Collectors.toList());
-            if (missingRegs.size() > 0)
+            ResourceLocation[] missingRegs = snapshot.keySet().stream().filter(name -> !RegistryManager.ACTIVE.registries.containsKey(name)).toArray(ResourceLocation[]::new);
+            if (missingRegs.length > 0)
             {
                 String header = "Forge Mod Loader detected missing/unknown registrie(s).\n\n" +
-                        "There are " + missingRegs.size() + " missing registries in this save.\n" +
+                        "There are " + missingRegs.length + " missing registries in this save.\n" +
                         "If you continue the missing registries will get removed.\n" +
                         "This may cause issues, it is advised that you create a world backup before continuing.\n\n";
 
@@ -617,13 +614,13 @@ public class GameData
 
         RegistryManager STAGING = new RegistryManager();
 
-        final Map<ResourceLocation, Map<ResourceLocation, IdMappingEvent.IdRemapping>> remaps = Maps.newHashMap();
-        final LinkedHashMap<ResourceLocation, Map<ResourceLocation, Integer>> missing = Maps.newLinkedHashMap();
+        final Map<ResourceLocation, Map<ResourceLocation, IdMappingEvent.IdRemapping>> remaps = new HashMap<>();
+        final LinkedHashMap<ResourceLocation, Object2IntMap<ResourceLocation>> missing = new LinkedHashMap<>();
         // Load the snapshot into the "STAGING" registry
         snapshot.forEach((key, value) ->
         {
-            remaps.put(key, Maps.newLinkedHashMap());
-            missing.put(key, Maps.newLinkedHashMap());
+            remaps.put(key, new LinkedHashMap<>());
+            missing.put(key, new Object2IntLinkedOpenHashMap<>());
             loadPersistentDataToStagingRegistry(RegistryManager.ACTIVE, STAGING, remaps.get(key), missing.get(key), key, value);
         });
 
@@ -634,11 +631,12 @@ public class GameData
             Multimap<ResourceLocation, ResourceLocation> defaulted = ArrayListMultimap.create();
             Multimap<ResourceLocation, ResourceLocation> failed = ArrayListMultimap.create();
 
-            missing.entrySet().stream().filter(e -> e.getValue().size() > 0).forEach(m ->
+            missing.entrySet().stream().filter(e -> !e.getValue().isEmpty()).forEach(m ->
             {
                 ResourceLocation name = m.getKey();
                 ForgeRegistry<?> reg = STAGING.getRegistry(name);
-                MissingMappingsEvent event = reg.getMissingEvent(name, m.getValue());
+                Object2IntMap<ResourceLocation> missingIds = m.getValue();
+                MissingMappingsEvent event = reg.getMissingEvent(name, missingIds);
                 MinecraftForge.EVENT_BUS.post(event);
 
                 List<MissingMappingsEvent.Mapping<?>> lst = event.getAllMappings(reg.getRegistryKey()).stream()
@@ -656,7 +654,7 @@ public class GameData
                         .filter(e -> e.action == MissingMappingsEvent.Action.FAIL)
                         .forEach(fail -> failed.put(name, fail.key));
 
-                processMissing(name, STAGING, event, m.getValue(), remaps.get(name), defaulted.get(name), failed.get(name), !isLocalWorld);
+                processMissing(name, STAGING, event, missingIds, remaps.get(name), defaulted.get(name), failed.get(name), !isLocalWorld);
             });
 
             if (!defaulted.isEmpty() && !isLocalWorld)
@@ -673,7 +671,7 @@ public class GameData
                 defaulted.asMap().forEach((name, entries) ->
                 {
                     buf.append("Missing ").append(name).append(":\n");
-                    entries.stream().sorted((o1, o2) -> o1.compareNamespaced(o2)).forEach(rl -> buf.append("    ").append(rl).append("\n"));
+                    entries.stream().sorted(ResourceLocation::compareNamespaced).forEach(rl -> buf.append("    ").append(rl).append("\n"));
                     buf.append("\n");
                 });
 
@@ -731,7 +729,7 @@ public class GameData
     }
 
     //Has to be split because of generics, Yay!
-    private static <T> void loadPersistentDataToStagingRegistry(RegistryManager pool, RegistryManager to, Map<ResourceLocation, IdMappingEvent.IdRemapping> remaps, Map<ResourceLocation, Integer> missing, ResourceLocation name, ForgeRegistry.Snapshot snap)
+    private static <T> void loadPersistentDataToStagingRegistry(RegistryManager pool, RegistryManager to, Map<ResourceLocation, IdMappingEvent.IdRemapping> remaps, Object2IntMap<ResourceLocation> missing, ResourceLocation name, ForgeRegistry.Snapshot snap)
     {
         ForgeRegistry<T> active  = pool.getRegistry(name);
         if (active == null)
@@ -743,7 +741,7 @@ public class GameData
     }
 
     //Another bouncer for generic reasons
-    private static <T> void processMissing(ResourceLocation name, RegistryManager STAGING, MissingMappingsEvent e, Map<ResourceLocation, Integer> missing, Map<ResourceLocation, IdMappingEvent.IdRemapping> remaps, Collection<ResourceLocation> defaulted, Collection<ResourceLocation> failed, boolean injectNetworkDummies)
+    private static <T> void processMissing(ResourceLocation name, RegistryManager STAGING, MissingMappingsEvent e, Object2IntMap<ResourceLocation> missing, Map<ResourceLocation, IdMappingEvent.IdRemapping> remaps, Collection<ResourceLocation> defaulted, Collection<ResourceLocation> failed, boolean injectNetworkDummies)
     {
         List<MissingMappingsEvent.Mapping<T>> mappings = e.getAllMappings(ResourceKey.createRegistryKey(name));
         ForgeRegistry<T> active = RegistryManager.ACTIVE.getRegistry(name);
@@ -755,9 +753,9 @@ public class GameData
     {
         ForgeRegistry<T> frozen = RegistryManager.FROZEN.getRegistry(name);
         ForgeRegistry<T> newRegistry = STAGING.getRegistry(name, RegistryManager.FROZEN);
-        Map<ResourceLocation, Integer> _new = Maps.newLinkedHashMap();
+        Object2IntMap<ResourceLocation> _new = new Object2IntLinkedOpenHashMap<>();
         frozen.getKeys().stream().filter(key -> !newRegistry.containsKey(key)).forEach(key -> _new.put(key, frozen.getID(key)));
-        newRegistry.loadIds(_new, frozen.getOverrideOwners(), Maps.newLinkedHashMap(), remaps, frozen, name);
+        newRegistry.loadIds(_new, frozen.getOverrideOwners(), new Object2IntLinkedOpenHashMap<>(), remaps, frozen, name);
     }
 
     /**
@@ -776,7 +774,7 @@ public class GameData
         String oldPrefix = index == -1 ? "" : name.substring(0, index).toLowerCase(Locale.ROOT);
         name = index == -1 ? name : name.substring(index + 1);
         String prefix = ModLoadingContext.get().getActiveNamespace();
-        if (warnOverrides && !oldPrefix.equals(prefix) && oldPrefix.length() > 0)
+        if (warnOverrides && !oldPrefix.equals(prefix) && !oldPrefix.isEmpty())
         {
             LogManager.getLogger().debug("Mod `{}` attempting to register `{}` to the namespace `{}`. This could be intended, but likely means an EventBusSubscriber without a modid.", prefix, name, oldPrefix);
             prefix = oldPrefix;