Office Applications Attempting WebDav when connecting to Legacy Shares?

Question

We have been getting users complaints about network performance. After checkeing servers and network equipement unable to find an issue, and checking back with users, we finally found out that the issue was when doing File/Open and browsing to legacy server shares, A connecting to server dialog box pops up and takes around 30-60 seconds to go on.

After doing some additional testing and network captures we discovered that Office is attempting HTTP/HTTPS requests to the servers. Specifically a WebDav PROPFIND request. If the server has a HTTP server running even without WebDAV support and replies the legacy share opens quickly. If it doesn't there is a long delay waiting for multiple requests to timeout. We can solve the user performance problem by installing IIS or another Web Server service on the servers. However I am hesitant to install another service opening up additional attack vectors to solve this. Has anyone found a setting within Office that I can change to make it stop attempting the WebDAV requests on the legacy file share servers?