Active directory role and file sharing

Hello,

I am experiencing for some time now "slow" file transfer from my Windows 2k8 server to Vista SP1 clients. Recently, I did some more tests and was finely able to point out the cause; the AD role is what cause the speed decreases.

When I copy a large file from my Win2k8 server with my Vista SP1 client it goes at about 130 meg/sec, but as soon as the server become a domain controller (AD role + dcpromo) clients are only able to copy at about half the initial speed (50 meg/sec).

As suggested in this forum, I tried to disable SMB2.0 and things went a little better, the speed rose up to 65 meg/sec.

I am pretty sure that this behaviors is more a feature than a bug (like the network bandwidth throttle in vista when a multimedia application is detected), but it actually bug me at this time. What is exactly changed by the AD role installer? Does it change the way SMB caching is used? Does it add bandwidth limitation? ... ?

How could I revert this change and get my full speed back?

I've done my tests on different servers with each time a clean install of Win2k8.

Here is my previous post about this issue: http://forums.technet.microsoft.com/en/winserverfiles/thread/1fa68306-fd2b-4fb3-ba47-5529b018ced4