I was recently working with documents stored in SharePoint (Office 365 to be exact) and was seeing poor performance when trying to open file types with applications other than Office. At first I just put it down to a slow connection to Office 365, but I quickly realised that accessing files from Office 365 via alternate means (CSOM, Web Services) was much faster. I also found that the ‘Open with Explorer’ function (available on the Library ribbon as shown below) was slow to open.
In both scenarios I saw the performance issue (1) Opening non-Office files from SharePoint, and (2) Using the Open in Explorer function, the underlying technology that is performing the communication is WebDAV. WebDAV is the layer that makes it possible for applications that were not designed to work with SharePoint to.. well.. work with SharePoint I guess! WebDAV is actually a standard and isn’t SharePoint specific but I won’t go into that here. Suffice to say I’d isolated my issue down to being a performance issue related to WebDAV.
Now I knew what I was troubleshooting, the answer was readily available. Here’s the official KB of a known issue with WebDAV and the auto-detect settings option in Internet Explorer http://support.microsoft.com/kb/2445570
This was the fix for me:
In Internet Explorer, open Internet Options
Select Connections | LAN Settings
Uncheck ‘Automatically detect settings’
That’s it. After making this change I could go back to SharePoint and the SharePoint Library ‘Open in Explorer’ action was 4x faster than it had been. I was also getting much faster opening times of my non-Office files.