Unity 4.3.4+ (Folders & Slow Editor Start/Stop)

Since I updated beyond Unity 4.3.4 I noticed that playing and stopping the editor takes ~20 seconds. After playing around a bit I figured out that it is related to folders that contain many objects. For example, if I have a tree folder and I place all the trees in the scene into it, the aforementioned bug rears its head. Taking all the trees out and the editor starts quicker, although it is still slower than with Unity 4.3.4.

I would stay on Unity 4.3.4 but there are a couple of assets that require a higher version to work. Unity devs, are you guys aware of this bug and is there a planned fix for it?

Bumping this one up again. I teach a Unity class at a University and the student projects have to avoid doing this because of it being so slow. Unity devs, can you please acknowledge this as an issue? Creating folders to place like items in is good organization and it currently is impossible do to the slowdown.