very slow opening windows share

It seems that whenever I try to open a shared directory on a windows system from a mini running Mavericks OS X 10.9.5 it takes a very long time and in some instances never displays the contents. On a very rare occasion it will open and display quickly. When I can open a directory and then try to copy something to it it will timeout and give me an error -51. I have been having this problem for months. In most cases I end up logging into the windows box and copy from the mini to the windows directory which works just fine. I saw somewhere that the type of SMB has be changed and I should be using CIFS. If that is the case does that mean I cannnot use the windows system listed in the shared section of Finder? Is there a fix for this problem? I don't want to move to Yosemite.

thanks

john