Paper/patches/server/0405-Don-t-run-entity-collision-code-if-not-needed.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Spottedleaf <Spottedleaf@users.noreply.github.com>
Date: Wed, 15 Apr 2020 17:56:07 -0700
Subject: [PATCH] Don't run entity collision code if not needed

Will not run if max entity craming is disabled and
the max collisions per entity is less than or equal to 0

diff --git a/src/main/java/net/minecraft/world/entity/LivingEntity.java b/src/main/java/net/minecraft/world/entity/LivingEntity.java
index 6cc2d26403aa5074218b4b76e2d8ed9e8409a0ae..0fd79c399e723b5a9db04c8f2fe7b6ec66c0cf44 100644
--- a/src/main/java/net/minecraft/world/entity/LivingEntity.java
+++ b/src/main/java/net/minecraft/world/entity/LivingEntity.java
@@ -3256,10 +3256,16 @@ public abstract class LivingEntity extends Entity {
     protected void serverAiStep() {}
 
     protected void pushEntities() {
+        // Paper start - don't run getEntities if we're not going to use its result
+        int i = this.level.getGameRules().getInt(GameRules.RULE_MAX_ENTITY_CRAMMING);
+        if (i <= 0 && level.paperConfig.maxCollisionsPerEntity <= 0) {
+            return;
+        }
+        // Paper end - don't run getEntities if we're not going to use its result
         List<Entity> list = this.level.getEntities(this, this.getBoundingBox(), EntitySelector.pushableBy(this));
 
         if (!list.isEmpty()) {
-            int i = this.level.getGameRules().getInt(GameRules.RULE_MAX_ENTITY_CRAMMING);
+            // Paper - move up
             int j;
 
             if (i > 0 && list.size() > i - 1 && this.random.nextInt(4) == 0) {