VDI Profile Loading Delays

We are noticing that it takes rather a long time for users to log in to our VDI environment (~2 minutes, in some circumstances).  I did some analysis of login times using Sysinternals Procmon.  (Enable boot logging, use the “view process tree” feature to look at process times at logon.  See http://blogs.technet.com/b/markrussinovich/archive/2012/07/02/3506849.aspx for details).  What I found was that a child process of explorer.exe called “ie4uinit.exe” was running for most of this time.  This process appears to be part of Microsoft “Active Setup” (discussed in some detail here: http://blog.ressoftware.com/index.php/2011/12/29/disable-active-setup-revealed/).

So what if we disable Active Setup?  Noise on the Internet suggests that this is possible , simply be deleting the key:
HKEY_LOCAL_MACHINESoftwareMicrosoftActive Setup
as suggested here:

However, there is some indication that this could have unintended consequences.  In my case, it immediately caused a logon script to fail to run.  Bummer!

What other solutions are possible?  Members of the Windows in Higher Education mailing list recently recommended using mandatory profiles.  There is a reasonably good rundown of the mandatory profile creation process here:
Missing details are:

  1. It is possible for the mandatory roaming profile to be stored locally (i.e. “C:UsersVDI_Mandatory.V2” to avoid over-the-network profile copy delays.  However, in our View environment, using a network location appears to be faster!
  2. The mandatory roaming profile can be specified using the Group Policy settings in Computer -> Policies -> Administrative Templates -> System -> User Profiles.  (See “Set roaming profile path for all users logging onto this computer” and “Delete cached copies of roaming profile”.)

In testing, I found initial logon times were reduced from two minutes to approximately 20 seconds.  Good!  (But still not great.)  Additional benefits are that it is no longer necessary to run the logon script that I developed to customize the Start Menu and Task Bar.  I also can remove the Group Policy preferences that clean up local profiles on the computer.