I am using Ubuntu 12.04 LTS and have a few CIFS mounts (mounted through fstab). When I open a LibreOffice file from these mounts, they open extremely slow, somewhere in the neighborhood of 1 to 2 minutes before I get to see the document. Saving is also slow.
It is not related to the share, because other programs (Text Editor, GIMP, etc) do not have this problem. If I copy the file locally, LibreOffice opens them with the expected speed.