Itween keep speed constant

how can i make this move a object at a constant speed all the time? because right now it slows down when it reaches the next waypoint.

 using UnityEngine;
 using System.Collections;
 
 public class follow : MonoBehaviour {
     public bool IsleftOn = false;
     public bool IsRightOn = false;
     private float smoothing = 0f;
     private Vector3 targetPosition;
 
     public float runSpeed = 0;
 
     public Transform[] path0;
     public Transform[] path1;
     public Transform[] path2;
 
     private Transform[][] paths = new Transform[3][];
     private int iPath = 1;
 
 
     float percentsPerSecond = 0.02f; // %2 of the path moved per second
     float currentPathPercent = 0.0f; //min 0, max 1
 
     void Start () {    
     paths[0] = path0;
     paths[1] = path1;
     paths[2] = path2;
     }
 
     void Update () {  
           IsleftOn = PlayMakerGlobals.Instance.Variables.GetFsmBool("leftcontrol").Value;
           IsRightOn = PlayMakerGlobals.Instance.Variables.GetFsmBool("rightcontrol").Value;
           runSpeed = PlayMakerGlobals.Instance.Variables.GetFsmFloat("playerspeed").Value;
            if  (IsleftOn == true) {
                 if (iPath == 2) iPath = 1; else iPath = 0;
                 PlayMakerGlobals.Instance.Variables.GetFsmBool("leftcontrol").Value = false;
 
            }
 
            else if (IsRightOn == true) {
                 if (iPath == 0) iPath = 1; else iPath = 2;
                 PlayMakerGlobals.Instance.Variables.GetFsmBool("rightcontrol").Value = false;
            }
        currentPathPercent += percentsPerSecond * Time.deltaTime * runSpeed;
        iTween.PutOnPath(gameObject, paths[iPath], currentPathPercent);
        transform.LookAt(iTween.PointOnPath(paths[iPath],currentPathPercent+.03f));
     }
 
     void OnDrawGizmos(){
        iTween.DrawPath(path0);
        iTween.DrawPath(path1);
        iTween.DrawPath(path2);
     }
 }