Very smooth unity cam

FlyCamSmooth

using UnityEngine;
using System.Collections;

/*
 * Based on http://www.blenderfreak.com/blog/post/flythrough-camera-smooth-movement-unity3d/
 *
 * Controls:
 *   WASD + R/F for Up/Down
 *   Mouse wheel control movement speed
 *   Mouse pointer is used for joystick like control of orientation
 *
 */

public class FlyCam : MonoBehaviour
{
	public float speed = 1.0f;
	public float sensitivity = 100f;
	public bool inverted = false;
	public float acceleration = 0.1f;

	private float actSpeed = 0.0f;
	private Vector3 lastDir = new Vector3();

    void Start()
    {
        Cursor.visible = false;
    }
	
	void Update ()
    {
		// Mouse Look
        var mouse = Input.mousePosition;
        mouse.x /= Screen.width;
        mouse.y /= Screen.height;
        mouse -= new Vector3(0.5f, 0.5f, 0.0f);
        mouse.x *= Mathf.Sign(mouse.x)*mouse.x;
        mouse.y *= Mathf.Sign(mouse.y)*mouse.y;
		if ( ! inverted ) mouse.y = -mouse.y;
		mouse *= sensitivity;
        mouse.y *= 0.5f;
		mouse = new Vector3( transform.eulerAngles.x + mouse.y, transform.eulerAngles.y + mouse.x, 0);
        var rot = transform.rotation;
        rot = Quaternion.Slerp(rot, Quaternion.Euler(mouse), 0.1f);
        transform.rotation = rot;

        // Speed
        speed += Input.GetAxis("Mouse ScrollWheel");

        // Direction
        Vector3 dir = Vector3.zero;
		if (Input.GetKey(KeyCode.W)) dir.z += 1.0f;
		if (Input.GetKey(KeyCode.S)) dir.z -= 1.0f;
		if (Input.GetKey(KeyCode.D)) dir.x += 1.0f;
		if (Input.GetKey(KeyCode.A)) dir.x -= 1.0f;
		if (Input.GetKey(KeyCode.R)) dir.y += 0.5f;
		if (Input.GetKey(KeyCode.F)) dir.y -= 0.5f;
		dir.Normalize();
		
        // Update translation
		if (dir.magnitude > 0.001f)
        {
			if (actSpeed < 1)
				actSpeed += acceleration * Time.deltaTime * 40;
			else 
				actSpeed = 1.0f;
			
			lastDir = dir;
		}
        else
        {
			if (actSpeed > 0)
				actSpeed -= acceleration * Time.deltaTime * 20;
			else 
				actSpeed = 0.0f;
		}
		transform.Translate( lastDir * actSpeed * speed * Time.deltaTime );
	}
}