So how exactly does it manage to draw the whole world in real time ?
When editing the child icons I mentioned that all the children should have their extents box within the boundary of the current icons extents. This is not strictly enforced by the app but it does lead to problems with display and screen saves if you don't do it. Its not strictly enforced because if you had some clear bit of the icons image over the edge then it does not matter and the app cant be bothered to keep looking at whether the image is clear or not when your moving.
When you have this hierarchy which is very deep going from the world down to small things like carts with hay bales on the back then the app has to draw that whole world except that its smart enough to know what it needs to and what it can ignore. Firstly anything that's too far off the left or right edges don't need to be drawn and things too small don't need to be either. So how small is too small ? Well that depends and thats what the Child Cut Off limit is all about.
When that option is put up then unlike most of the dialog options, this one a) gets rid of all the parent dialogs leaving just itself behind and b) normally when you open a dialog then it sorta blurs the map but with this one it does not.
It has a red bar and a + and - button. By moving the slider to more and less then when it draws the screen it cuts off drawing small icons based on this limit. Sometimes you really want to see all the detail in the map. So go for a small setting. Sometimes its better if it cuts off the child hierarchy levels much quicker so go large.
When its small the map has more to draw and might take longer if it has a lot of small stuff on it. So to some extent it matters what speed your PC / graphics card is too for the right setting.
Now if a level in your hierarchy is too far to the left or right so that none of it is within the draw area then not only is that icon not displayed but the app assumes that since all the children of it were also within that icon then it does not have to go down any farther and clip the whole hierarchy tree off at that point. So had you have had some children off to the right of an icons boundary and then moved that icon off the screen left then that child would suddenly vanish when its parent left the draw area. So that's why you should not do it.
Now given that in any one scene if you have an area with very small regions on it that have even smaller battle maps going on then it makes no difference how complicated those battle maps are because it wont try to draw them anyway. As you move in on them then sure they need to be drawn but some of the other stuff has moved out of view so now does not. At a certain level of PC / Graphics card power you find that all but the most contrived scenes can be done at a real time rate - and fortunately, so long as we don't squander that power, that's where we are now. :)
Note the chests in this set of four images as we zoom out. Now the app doesn't just pop too small icons out in a blink. It fades them out so that it looks a little nicer. I should also add that this is with the Child Cut Off set quite high because normally its set to fade out at just a few pixels.