From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Jake Potrebic <jake.m.potrebic@gmail.com>
Date: Sun, 20 Mar 2022 22:06:47 -0700
Subject: [PATCH] Cache resource keys and optimize reference Holder tags set

TagKeys are always interned, so we can use a reference hash set for them

diff --git a/src/main/java/net/minecraft/core/Holder.java b/src/main/java/net/minecraft/core/Holder.java
index d7bbf60ba94ecd85f991a0c5c70c34fdb00ec9d5..4d2231868b786da9071c3dff2c073b478a486e8a 100644
--- a/src/main/java/net/minecraft/core/Holder.java
+++ b/src/main/java/net/minecraft/core/Holder.java
@@ -221,7 +221,7 @@ public interface Holder<T> {
         }
 
         void bindTags(Collection<TagKey<T>> tags) {
-            this.tags = Set.copyOf(tags);
+            this.tags = java.util.Collections.unmodifiableSet(new it.unimi.dsi.fastutil.objects.ReferenceOpenHashSet<>(tags)); // Paper
         }
 
         @Override
diff --git a/src/main/java/org/bukkit/craftbukkit/block/CraftBiome.java b/src/main/java/org/bukkit/craftbukkit/block/CraftBiome.java
index 95b956802f83b583a823fcd24808363775a56842..33d2e89ac40465b0c4633f9c51378b80f7c397a9 100644
--- a/src/main/java/org/bukkit/craftbukkit/block/CraftBiome.java
+++ b/src/main/java/org/bukkit/craftbukkit/block/CraftBiome.java
@@ -3,6 +3,7 @@ package org.bukkit.craftbukkit.block;
 import com.google.common.base.Preconditions;
 import net.minecraft.core.Holder;
 import net.minecraft.core.registries.Registries;
+import net.minecraft.resources.ResourceKey;
 import org.bukkit.Registry;
 import org.bukkit.block.Biome;
 import org.bukkit.craftbukkit.CraftRegistry;
@@ -27,13 +28,14 @@ public class CraftBiome {
         return CraftBiome.minecraftToBukkit(minecraft.value());
     }
 
+    private static final java.util.Map<org.bukkit.block.Biome, ResourceKey<net.minecraft.world.level.biome.Biome>> BIOME_KEY_CACHE = java.util.Collections.synchronizedMap(new java.util.EnumMap<>(Biome.class)); // Paper
     public static net.minecraft.world.level.biome.Biome bukkitToMinecraft(Biome bukkit) {
         if (bukkit == null || bukkit == Biome.CUSTOM) {
             return null;
         }
 
         return CraftRegistry.getMinecraftRegistry(Registries.BIOME)
-                .getOptional(CraftNamespacedKey.toMinecraft(bukkit.getKey())).orElseThrow();
+                .getOptional(BIOME_KEY_CACHE.computeIfAbsent(bukkit, b -> ResourceKey.create(Registries.BIOME, CraftNamespacedKey.toMinecraft(b.getKey())))).orElseThrow();
     }
 
     public static Holder<net.minecraft.world.level.biome.Biome> bukkitToMinecraftHolder(Biome bukkit) {
diff --git a/src/main/java/org/bukkit/craftbukkit/entity/CraftEntityType.java b/src/main/java/org/bukkit/craftbukkit/entity/CraftEntityType.java
index fd1aaf8e18d6e3425639b60ce21c5aaf36e0b42a..266b616419a47f518a43b990cc7cbb4516beda03 100644
--- a/src/main/java/org/bukkit/craftbukkit/entity/CraftEntityType.java
+++ b/src/main/java/org/bukkit/craftbukkit/entity/CraftEntityType.java
@@ -24,11 +24,11 @@ public class CraftEntityType {
         return bukkit;
     }
 
+    private static final java.util.Map<EntityType, net.minecraft.resources.ResourceKey<net.minecraft.world.entity.EntityType<?>>> KEY_CACHE = java.util.Collections.synchronizedMap(new java.util.EnumMap<>(EntityType.class)); // Paper
     public static net.minecraft.world.entity.EntityType<?> bukkitToMinecraft(EntityType bukkit) {
         Preconditions.checkArgument(bukkit != null);
-
         return CraftRegistry.getMinecraftRegistry(Registries.ENTITY_TYPE)
-                .getOptional(CraftNamespacedKey.toMinecraft(bukkit.getKey())).orElseThrow();
+                .getOptional(KEY_CACHE.computeIfAbsent(bukkit, type -> net.minecraft.resources.ResourceKey.create(Registries.ENTITY_TYPE, CraftNamespacedKey.toMinecraft(type.getKey())))).orElseThrow();
     }
 
     public static String bukkitToString(EntityType bukkit) {