[CrazY.]

You can probably replace client_PreThink with Ham_Player_Jump.
Both are called once per frame but Ham_Player_Jump only if a player has the jump key held

/**
	 * Players have all the attributes of normal entities, in addition to these.
	 */
	 
	/**
	 * Description:		Typically called every frame when a player has jump held.
	 * Forward params:	function(this)
	 * Return type:		None.
	 * Execute params:	ExecuteHam(Ham_Player_Jump, this);
	 */
	Ham_Player_Jump,