Very slow responce when working with Office file on DFS-Share

Question

Very slow responce when working with Office file on DFS-Share
We have implemented the following configuration
Domain level Windows 2000. Two member servers with Windows Server 2008 R2, sharing the same DFS namespace with, at the moment, one folder target called Home.
Users complaining that the access to different MS Office files is very slow. Even creating a new MS Word document using right click context menu takes up to 4 minutes to open. Saving, for example, one singe Excel sheet takes also few minutes.
Tested with both, MS Office 2007 and MS Office 2010. Makes no difference. When using Office 2010 you can see the message like contacting:
\\DomainName\Root\Home\UserName. Other files like TXT, JPG or PDF are not affected.
 What makes the thing really weird is the fact, that the behavior described above can absolutely change after client machine being rebooted, suddenly everything becomes very fast and this condition can revert back again just after the next
reboot.
Considerations until now:
1. This has nothing to do with the file size. Even tiny files are affected.
2. AD Sites are configured correctly and the client workstations see themselves in the correct sites.
3. This is not an Office issue. If I map my folder target not as DFS, but directly as shared network drive
\\ServerName\Root\Home\UserName , everything functions as expected
What makes me suspicious: when using f.e. TCPView to monitor connections, I can see, that each time I make any operation on an office file, there will be a connection established to one of the domain controllers, sometimes to remote ones,
located in other countries. But on the other side, even if the connection is established to the nearest DC, operations are still very very slow!
Just forget to say. All clients are Windows 7
Thanks to all who respond.

Answer 1

Dear all,
sorry for the delayed reply. The problem has been solved now and since September 19^th. everything is functioning as expected.
What was done:
Deleted replication targets excepting the initial ones
Carefully recreated folder targets
Deleted and recreated  replication groups
Disabled SNP features on both namespace servers
Created EnableTCPA registry entry
Checked that the following Updates are installed
http://support.microsoft.com/kb/2688074
http://support.microsoft.com/kb/2647452
Concering Office File validation KB2553065 - This Update was already declined on our WSUS server
Kind Regards
Eduard