Slow opening of Excel 2010 on 2012 server

Hi

I am new to Server 2012.  

I have set up a 2012 server as a file server with 12gb, added to domain.
I have several old 2003 servers in domain.
My existing DC's are both 2003.
I have moved a data share from one of my 2003 servers onto the 2012 file server.

But when we open up or save an Excel 2010 spread sheet it takes at least 10 seconds, if I save its even longer.
If I open up the same file that's still on old server it is instantly opened.  
I have also another 2012 server not yet joined to domain, and that is also slow.
I know the permissions are all ok, as it eventually opens.
It seems file sharing role is automatically set up, and I cant see any other role I need?

Please can you help.

I have since tried to replicate the scenario at my offices, but it all works fine here.

Thanks Terry