Create Texture2D dynamic objects cause memory leak?

There's a simple test code for the problem, I tested on Unity5 & Win8:

Try to create some Texture2D dynamic objects and then release , memory looks well in Editor Profiler, but increases crazily in Windows Task Manager.

 using UnityEngine;
 
 public class TestMemoryLeak : MonoBehaviour {
 
     float _nextCalcTime;
 
     System.Random random = new System.Random();
 
     void Update ()
     {
         if (Time.time >= _nextCalcTime) {
             int size = 1024 + random.Next(-100, 100);
             Texture2D tex = new Texture2D(size, size, TextureFormat.ARGB32, false);

             DestroyImmediate(tex, true);
             Resources.UnloadUnusedAssets();
             System.GC.Collect();
 
             _nextCalcTime = Time.time + 1f;
         }
         
     }
 }