I have the AD admin complaining that the Unity 5 install has a large number of advanced permssions for the DirSvc and MessageStoreMgr accounts (85 entries in total for each AD object). Some of these appear to be empty entries. I advised not to touch them even if they appear empty since it may disable Unity functionality. Have any other Unity 5 installs encountered this and is it an issue to have so many permissions?
The number of permissions added depends on several factors including active directory version (2000/2003), number of message stores, etc. Take a look at the following link. Specifically, see the "Estimating the Size Impact of Permissions on the Active Directory Database" section.
Also, be aware that if you are using Windows 2000 domain controllers, you may experience "ACL bloat" causing the AD database to grow to twice or more its original size. This is also explained in the link above.
Hope this helps. If so, please rate the post.