skill mob rate not working properly

[testconta 0]

I would like to set up a mob to instantly use skill as an example Asura strike when getting close to any player. I tried to configure it but even though the rate is 100% it takes a LOT of time for the asura strike to come out.

1001,Scorpion@MO_EXTREMITYFIST,attack,271,5,10000,500,20,no,target,always,0,,,,,,18,

1001,Scorpion@MO_EXTREMITYFIST,chase,271,5,10000,500,20,no,target,always,0,,,,,,18,
1001,Scorpion@MO_EXTREMITYFIST,idle,271,5,10000,500,20,no,target,always,0,,,,,,18,
1001,Scorpion@MO_EXTREMITYFIST,attack,271,5,10000,500,20,no,target,always,0,,,,,,18,

[AnnieRuru 958]

{
	Id: 1001
	SpriteName: "SCORPION"
	Name: "Scorpion"
	Lv: 16
	Hp: 153
	Sp: 1
	Exp: 108
	JExp: 81
	AttackRange: 1
	Attack: [33, 7]
	Def: 16
	Mdef: 5
	Stats: {
		Str: 12
		Agi: 15
		Vit: 10
		Int: 5
		Dex: 19
		Luk: 5
	}
	ViewRange: 10
	ChaseRange: 12
	Size: "Size_Small"
	Race: "RC_Insect"
	Element: ("Ele_Fire", 1)
	Mode: {
		CanMove: true
		CastSensorIdle: true
		CanAttack: true
		Detector: true
		ChangeTargetMelee: true
		ChangeTargetChase: true
	}
	MoveSpeed: 200
	AttackDelay: 1
	AttackMotion: 1
	DamageMotion: 1
	MvpExp: 0
	Drops: {
		Boody_Red: 70
		Scorpions_Tail: 5500
		Elunium_Stone: 57
		Solid_Shell: 210
		Fine_Grit: 100
		Yellow_Herb: 200
		Lusty_Iron: 20
		Scorpion_Card: 1
	}
},

	SCORPION: {
		NPC_FIREATTACK: {
			SkillState: "MSS_BERSERK"
			SkillLevel: 1
			Rate: 2000
			Delay: 5000
			Cancelable: true
			SkillTarget: "MST_TARGET"
			CastCondition: "MSC_ALWAYS"
		}
		NPC_POISON: {
			SkillState: "MSS_BERSERK"
			SkillLevel: 1
			Rate: 500
			CastTime: 800
			Delay: 5000
			SkillTarget: "MST_TARGET"
			CastCondition: "MSC_ALWAYS"
		}
		NPC_POISONATTACK: {
			SkillState: "MSS_BERSERK"
			SkillLevel: 1
			Rate: 500
			CastTime: 300
			Delay: 5000
			SkillTarget: "MST_TARGET"
			CastCondition: "MSC_ALWAYS"
		}
		MO_EXTREMITYFIST: {
			SkillState: "MSS_ANY"
			SkillLevel: 5
			Rate: 10000
			CastTime: 0
			Delay: 0
			SkillTarget: "MST_TARGET"
			CastCondition: "MSC_ALWAYS"
		}
	}

you also need to lower monster's AttackDelay and AttackMotion for the monster to cast skill faster too