Diablo 3 like move to mouse (w/o click) - efficient?

I'm working on a Diablo like, topdown view and want the player to have the option of rotating/moving without having to click anything by using mousePosition. I'm not much of a programmer but I've read some of the Expert answers to similar questions and put together the following C# based on those, and it's working fine. Since there are (frequently) times where I don't really understand the code, my question is: Does this look efficient?

 using UnityEngine;
 using System.Collections;
 
  
 public class xLookMoveMouse : MonoBehaviour
 {
      private Transform thisTransform;
     public CharacterController cc;        // drag in editor
     public float rotSpeed;                // set in editor
     public float walkSpeed;                // set in editor
     public float runSpeed;                // set in editor
     public float distIdle;                // set in editor; baseline 14 (~200)
     public float distWalk;                // set in editor; baseline 22 (~500)
                                         // distRun need not be declared
     void Start () {
         thisTransform = transform;
     }
     
     void FixedUpdate () 
     {
         
         // If Left Shift is down none of this occurs; modify to suit
             
         if(!Input.GetKey (KeyCode.LeftShift)) {        
             
             // Generate a plane that intersects the transform's position with an upwards normal.
             Plane playerPlane = new Plane(Vector3.up, thisTransform.position);
             
             Vector3 mousePos = Input.mousePosition;
      
             // Generate a ray from the cursor position
             Ray ray = Camera.main.ScreenPointToRay (mousePos);
      
             // Determine the point where the cursor ray intersects the plane.
             // This will be the point that the object must look towards to be looking at the mouse.
             // Raycasting to a Plane object only gives us a distance, so we'll have to take the distance,
             //   then find the point along that ray that meets that distance.  This will be the point
             //   to look at.
             float hitdist = 0.0f;
             // If the ray is parallel to the plane, Raycast will return false.
             if (playerPlane.Raycast (ray, out hitdist)) 
             {
                 // Get the point along the ray that hits the calculated distance.
                 Vector3 targetPoint = ray.GetPoint(hitdist);
      
                 // Determine the target rotation.  This is the rotation if the transform looks at the target point.
                 Quaternion targetRotation = Quaternion.LookRotation(targetPoint - thisTransform.position);
      
                 // Smoothly rotate towards the target point.
                 transform.rotation = Quaternion.Slerp(thisTransform.rotation, targetRotation, rotSpeed * Time.deltaTime);
                 Vector3 forward = thisTransform.TransformDirection(Vector3.forward);
             
                 // Determine distance from mouse for idle/walk/run
                 Vector3 mouseDistance=(thisTransform.position - targetPoint);
                 float mouseSqr = mouseDistance.sqrMagnitude;
                 
                 if(mouseSqr < distIdle*distIdle) {
                 // do nothing, play idle animation, etc
                 }
                 
                 if(mouseSqr>=(distIdle*distIdle) && mouseSqr < (distWalk*distWalk)){
                 // play walk animation, etc
                   cc.SimpleMove(forward * walkSpeed);
                 }
                 
                 if(mouseSqr>=(distWalk*distWalk)) {
                 // play run animation, etc
                  cc.SimpleMove(forward * runSpeed);
                 }
             }
         }
     }
 }

The main camera is not a child of the player, the default MouseLook scripts have been removed from the player/camera, Camera Field of View is 35 with rot 60,0,0, a RigidBody is assigned to player with rot/pos locked & no gravity, and this script is attached to the main camera:

 using UnityEngine;
 using System.Collections;
  
 public class xLook : MonoBehaviour {
     
     public Transform playerTransform;
     public Vector3 cameraOrientationVector = new Vector3 (0, 130, -72f);                // change in editor to suit
     private Transform thisTransform;
      
     void Start () {
     
         thisTransform = transform;
     }
      
     void LateUpdate () {
      
         thisTransform.position = playerTransform.position + cameraOrientationVector;
      
     }
 }

Almost none of this is my work instead it's pulled from other sources (wish I had kept URL as references/credit). I did see many posts asking for help on something like this usually wanting to move via mouse click. However, since I'm not using a mouseclick I am concerned about the performance of all that stuff going on in FixedUpdate.

Added Camera fov/rot info.