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 94671ea227b59a8f820425c401712e6aeb8b2b10..e91c4e26c25980645941ca8fbdcc3a9d02e31063 100644
--- a/src/main/java/net/minecraft/core/Holder.java
+++ b/src/main/java/net/minecraft/core/Holder.java
@@ -230,7 +230,7 @@ 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/entity/CraftEntityType.java b/src/main/java/org/bukkit/craftbukkit/entity/CraftEntityType.java
index 6cf8af0c85231de9955282d4abaa0607ec9a195c..d230cbc26f61d8ac5880825aca4dfab197c20401 100644
--- a/src/main/java/org/bukkit/craftbukkit/entity/CraftEntityType.java
+++ b/src/main/java/org/bukkit/craftbukkit/entity/CraftEntityType.java
@@ -25,11 +25,11 @@ 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 Holder<net.minecraft.world.entity.EntityType<?>> bukkitToMinecraftHolder(EntityType bukkit) {