60FPS but the game seems lagging

Hi, i made a game, not much complex (with grap$$anonymous$$cs or scripts) but nice. I found a script that shows fps in the game :

 using UnityEngine;
 using System.Collections;
 
 public class fpsshow : MonoBehaviour
 {
     float deltaTime = 0.0f;
 
     void Update()
     {
         deltaTime += (Time.deltaTime - deltaTime) * 0.1f;
     }
 
     void OnGUI()
     {
         int w = Screen.width, h = Screen.height;
 
         GUIStyle style = new GUIStyle();
 
         Rect rect = new Rect(0, 0, w, h * 2 / 100);
         style.alignment = TextAnchor.UpperLeft;
         style.fontSize = h * 2 / 100;
         style.normal.textColor = new Color (0.0f, 0.0f, 0.5f, 1.0f);
         float msec = deltaTime * 1000.0f;
         float fps = 1.0f / deltaTime;
         string text = string.Format("{0:0.0} ms ({1:0.} fps)", msec, fps);
         GUI.Label(rect, text, style);
     }
 }

it shows me (in the build) 63-4 to 70 fps never under 60s (the same if I try the game in the Unity editor with stats active) I even turned down the quality settings a bit (but i t$$anonymous$$nk that is not that the probem, because the game uses 7% of the cpu and 70mb of ram, I have a gt 920m, w$$anonymous$$ch is enough for t$$anonymous$$s game), but sometimes the game seems lagging or stuttering. I don't know why... the camera movement is in the LateUpdate Function, and the player dosen't move with animations but with phyiscs (rigidbody). (my fixed delta time is 0.01 s).

(I even don't know why the "fpsshow" when the game is in the pause menu, timescale 0, shows infinity fps)

Thanks