Microsoft Office VERY Slow Opening Files on Network Shares

I manage several computers running Windows 7 with Microsoft Office 2010 and Microsoft Office 2013. Our users store and access many of the Microsoft Office files on a network share. For a typical file around 100KB:

1. Copying the file from the network drive to a local drive: < 1s.
2. Opening the file with Notepad: < 1s.
3. Opening the file with LibreOffice < 1s.
4. Copying the file to a local drive and then opening it locally: < 1s.
5. Opening the file with Microsoft Office (e.g. Word for .docx): < 20s.

In the last case, the dialog shows "Downloading ... (0%)" and hangs there until the file finally opens. Obviously, from results 1-3, this is not reflective of the network drive performance.

I have followed instructions from here, adjusting the Office version number as needed. This seems to describe the problem well, but the fix doesn't work.

I have also tried various one-off registry edits to disable validation. They also do not work, but I'm open to any suggestions.

The network shares are shared by Samba 3. Some of the client machines are running antivirus and some aren't running any at all, so that can't be the issue.

Can anybody offer any thoughts? I don't care about security scanning the files, checking whether they're valid, or any other such operations. I just need Microsoft Office programs to open the files in a reasonable time, so even the most heavy-handed working solution will be fine.

I experienced this lots in our network. We solved this with a few sets of instructions:

1. Disable any extra Office cruft or add ons - especially the Adobe Acrobat add on. This sped up most Office slow downs. To verify if this opens it quicker, start your Office program, then use the File->Open dialog to choose a file on your server. If it's fast, it's an add-on's fault.
2. Keep the updates up to date. An out of date Office 2007 install was taking 2 minutes to open a file from our Samba server. After installing updates, only a few seconds.
3. I used to use oplocks in my smb.conf file, but have since removed them. Try with a fresh share, documents of every size.