[ANDROID] Downloading large (4000x4000) textures causes a lot of memory consumption.

So, we're developing a game where we need to download for each game a certain gif. We have split these gifs into spritesheets and they are stored in our database, w$$anonymous$$ch we can access through the Rest communicating with Server.

Problem: After I load a spritesheet from the outside, thats about 4000x4000 pixels, the game eats like 100MB of RAM, w$$anonymous$$ch is a problem here. Here is a snippet of my code:

     private IEnumerator LoadImageFromURL(_AnimatedSprite a)
     {
         Debug.Log("Checking url");
         WWW www;
         
         if(a.HasThumbnail)
         {
            www = new WWW(a.URL);
         }
 
         else
         {
             www = new WWW(a.URLThumnail);
         }
         
        
         Debug.Log("Started downloading");
          
         yield return www;
 
         if (www.error != null)
         {
               Debug.Log("Error!");
               Switcher.mb.showMessage(MessageBox.MessageType.negative, www.error);
               a.Loaded = true;  
             running = false;
         }
 
         else
         {
                 
             if (!a.HasThumbnail)
             {
                 www.LoadImageIntoTexture(a.Thumbnail);
                 
                 // a.Thumbnail.LoadImage(www.bytes);
                // a.Thumbnail.Compress(false);
                 a.HasThumbnail = true;
             }
             
             else
             {
                 www.LoadImageIntoTexture(a.SpriteSheet);
                 // a.SpriteSheet.LoadImage(www.bytes);
                // a.SpriteSheet.Compress(true);
                 a.Loaded = true;
             }
    
             Texture2D.Destroy(www.texture);
             Texture2D.Destroy(www.textureNonReadable);
             Resources.UnloadUnusedAssets();
         }
         
         running = false;
         www.Dispose();
         www = null;
         string s = a.HasThumbnail ? "animation" : "thumbnail";
         Debug.Log("Finished downloading " + s);
     }

Any help is appreciated. Thanks!