Paper/patches/server/0838-Optimize-player-lookups-for-beacons.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Spottedleaf <Spottedleaf@users.noreply.github.com>
Date: Thu, 6 Jul 2023 20:17:37 -0700
Subject: [PATCH] Optimize player lookups for beacons

For larger ranges, it's better to iterate over the player list
than the entity slices.

diff --git a/src/main/java/net/minecraft/world/level/block/entity/BeaconBlockEntity.java b/src/main/java/net/minecraft/world/level/block/entity/BeaconBlockEntity.java
index b6633ca1ee73ef0f8a220992a2e0424e67dd9758..814e70f558d7a6186233da0ff86c94c95d390e09 100644
--- a/src/main/java/net/minecraft/world/level/block/entity/BeaconBlockEntity.java
+++ b/src/main/java/net/minecraft/world/level/block/entity/BeaconBlockEntity.java
@@ -333,7 +333,22 @@ public class BeaconBlockEntity extends BlockEntity implements MenuProvider, Name
             double d0 = blockEntity != null ? blockEntity.getEffectRange() : (i * 10 + 10); // Paper - Custom beacon ranges
 
             AABB axisalignedbb = (new AABB(blockposition)).inflate(d0).expandTowards(0.0D, (double) world.getHeight(), 0.0D);
-            List<Player> list = world.getEntitiesOfClass(Player.class, axisalignedbb);
+            // Paper start - Perf: optimize player lookup for beacons
+            List<Player> list;
+            if (d0 <= 128.0) {
+                list = world.getEntitiesOfClass(Player.class, axisalignedbb);
+            } else {
+                list = new java.util.ArrayList<>();
+                for (Player player : world.players()) {
+                    if (player.isSpectator()) {
+                        continue;
+                    }
+                    if (player.getBoundingBox().intersects(axisalignedbb)) {
+                        list.add(player);
+                    }
+                }
+            }
+            // Paper end - Perf: optimize player lookup for beacons
 
             return list;
         }