From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: MrPowerGamerBR <git@mrpowergamerbr.com>
Date: Wed, 15 Nov 2023 23:39:36 -0300
Subject: [PATCH] Skip "distanceToSqr" call in "ServerEntity#sendChanges" if
 the delta movement hasn't changed

The "distanceToSqr" call is a bit expensive, so avoiding it is pretty nice, around ~15% calls are skipped with this check

We could also check if the x,y,z coordinates are equal, but for now, let's just keep the identity check, which also helps us since Minecraft's code does reuse the original delta movement Vec3 object

diff --git a/src/main/java/net/minecraft/server/level/ServerEntity.java b/src/main/java/net/minecraft/server/level/ServerEntity.java
index bfdd0ce9acfae75a403d3689b391dd8fff7416a0..71d6f63feb8548181882c481f53c810baf8c1e07 100644
--- a/src/main/java/net/minecraft/server/level/ServerEntity.java
+++ b/src/main/java/net/minecraft/server/level/ServerEntity.java
@@ -215,12 +215,14 @@ public class ServerEntity {
 
                 if ((this.trackDelta || this.entity.hasImpulse || this.entity instanceof LivingEntity && ((LivingEntity) this.entity).isFallFlying()) && this.tickCount > 0) {
                     Vec3 vec3d1 = this.entity.getDeltaMovement();
+                    if (vec3d1 != this.ap) { // SparklyPaper start - skip distanceToSqr call in ServerEntity#sendChanges if the delta movement hasn't changed
                     double d0 = vec3d1.distanceToSqr(this.ap);
 
                     if (d0 > 1.0E-7D || d0 > 0.0D && vec3d1.lengthSqr() == 0.0D) {
                         this.ap = vec3d1;
                         this.broadcast.accept(new ClientboundSetEntityMotionPacket(this.entity.getId(), this.ap));
                     }
+                    } // SparklyPaper end
                 }
 
                 if (packet1 != null) {