Slow SMB connection Buffalo Linkstation
The problem is caused by Apple's home-made implementation of the smb protocol.  Using smb3 won't make a difference.

Server-Side Fix

If you have control of the smb server (Samba?) then you can fix this issue by enabling the vfs_fruit module.  If you are not using Samba then you'll need to find another way to enable "Alternate Data Streams" (ADS) and intercept OSX's "special" streams: AFP_AfpInfo and AFP_Resource.  I made notes of all the details at the plazko.io blog.
On Samba server you can fix the issue by enabling vfs_fruit in smb.conf like this:

vfs objects = fruit streams_xattr


From the vfs_fruit manpage:


  The module enables alternate data streams (ADS) support for a share,
   intercepts the OS X special streams "AFP_AfpInfo" and "AFP_Resource"
   and handles them in a special way. All other named streams are deferred
   to vfs_streams_xattr which must be loaded together with vfs_fruit.
  
  Having shares with ADS support enabled for OS X client is worthwhile
   because it resembles the behaviour of Apple's own SMB server
   implementation and it avoids certain severe performance degradations
   caused by Samba's case sensitivity semantics.


Important note for novices: This fix needs to be done on the server side.  If you do not have control of the smb server (presumably Samba) then you will not be able to use this fix.

Client-Side Fix

If you do not have control of the smb server, then your only option is to change the way the OSX client is handling smb.  The only way to do that is to replace Apple's implementation of the smb stack with Samba.  I have never done this, but there is a tutorial here.