2012 R2 / Win 7 - Slow accessing network resources

Dear Experts,

We recently migrated our SBS 2008 DC to a 2012 R2 DC, and pushed the mail to O365.

Since the SBS was decommissioned/demoted yesterday, we are experiencing the following issues:
- Slow opening applications (word, excel etc)
- Slow opening or saving files
- Slow opening attachments in Outlook
- Slow discovering local and mapped drives in Windows explorer

The new DC resumed the DNS, DHCP roles.

Interestingly, when I disable my NIC and try to open local files, programs, Outlook attachments, windows explorer etc, all returns to the usual snappy speed.

All the clients are Windows 7 x64

Please advise where I should start looking.

Thanks in advance all!
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Carol ChisholmCommented:
Make sure no references remain to the old SBS DNS server on workstations or servers or in DHCP
Check your reverse DNS in your new for duplicate incorrect entries

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JohnBusiness Consultant (Owner)Commented:
I am at a client with Server 2012 (new in the last 60 days) and Windows 7 workstations. All is well.

Server 2012 has two NIC's and we needed to disable the unused NIC.
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