How does setting the hideFlags resolve leaking issues? (Texture 2D leaking)

Thanks for your answer. Couple of things though, can't I 'take care of it' without setting the flags? where 'taking care' means manually destroying the object.

Also, the object isn't 'really' lost, otherwise how would unity know it's been leaked? ;)

Finally, I noticed that with these leaks around, first thing: the longer I have unity opened, the more stuff gets leaked (like first it starts leaking a couple of textures, and then hundreds!) second thing: the longer I keep Unity open the slower it becomes with time (compiling becomes really slow....) - which brings the question: Is unity 'really' cleaning up?! if so why the slow down?...

This is true, you can take care of it but Unity will still complain and spit errors at you because it doesn't know you are going to manage that object. And yes you are correct, it isn't lost, you are referencing it from your script and Unity is aware of everything that it creates. What I meant was it isn't connected to anything in the scene.

Your problem sounds like one I had when I was editing materials. Each time I edited the material on a render it would create a new modified material out of the shared material and since I wasn't first assigning the material to my own variables it would just make one and let it out into the open! A scary thought that.

Since you are dealing with textures and I haven't seen the code it really could be anything else. I would try setting the flags to get rid of the errors. If the debug log is really going at it and gets really loaded that is going to slow things down a ton. If it still slows down it is probably something funny going on where textures are being generated and you don't know about it. Submit your code and we can take a look and see if there is a problem somewhere.

Well TBH, I did try the set the flags and institute textures in OnEnable and destroy in OnDisable and so far I'm not getting any leak messages. But I was just arguing to try and make sense of things.

Also fortunately there's not a lot of places where I'm creating textures also my code is well encapsulated so it's easy to track things down - I usually create textures for my editor styles via:

 public static Texture2D GetTexture(Color color, HideFlags flags)
 {
     var texture = new Texture2D(1, 1);
     texture.SetPixel(0, 0, color);
     texture.Apply();
     texture.hideFlags = flags;
     return texture;
 }

ex:

 public static GUIStyle SelectedStyle
 {
     get
     {
         if (selectedStyle == null || selectedStyle.normal.background == null)
             selectedStyle = new GUIStyle(GUI.skin.textField)
             {
                 alignment = TextAnchor.$$anonymous$$iddleLeft,
                 margin = new RectOffset(0, 0, 0, 0),
                 padding = new RectOffset(0, 0, 4, 4),
                 normal = new GUIStyleState
                 {
                     background = Utils.GetTexture(61, 128, 223, 255, HideFlags.DontSave),
                     textColor = Color.white
                 }
             };
         return selectedStyle;
     }
 }