First, visit OneDrive on the web, sign-in and click the Files link in the top left. When you do, the address bar will display a URL that includes a “cid” number, like so. (I’ve altered this number so that it is not my real cid number.)
Make a note of the cid part of that URL, or just keep the browser open so you can copy and paste it later.
Now, open File Explorer (or, in Windows 7, Windows Explorer), navigate to the This PC view (Computer, in older OS versions) and click Map Network Drive in the ribbon/toolbar. (If the ribbon is hidden by default, you will need to open it first.)
When you do, the Map Network Drive wizard appears.
Select a drive letter (perhaps O: for OneDrive, your call) and then add this to the Folder field:
(Where YOUR-CID is of course replaced with your actual cid number.) Make sure “Reconnect at sign-in” remains selected and then click Finish.
You’ll be prompted to enter your OneDrive credentials—that is, your Microsoft account name (like email@example.com or whatever) and password—but if you’ve added the correct protections (two-step verification) to your account, you’ll need to create an app password at the Microsoft Account web site first: navigate to the Security settings page to do so.
When you do sign-in, a new drive will appear in File Explorer, in the This PC view, with a name that matches that cid number. You might want to rename it to something that makes a bit more sense.
Now, you can access the contents of your OneDrive normally, if slowly. It’s all there. You can copy/move back and forth to this location, access OneDrive directly from apps like Word, and do any other file operation you normally use.
Beside performance, the other caveat is that this is an online view only: if the PC is offline, you can’t access your OneDrive files and folders.
I know there are various third party solutions for accessing OneDrive in File Explorer, but I’ve found them to be slow as well. If you know of something more elegant than this, please do let me know. As I test Windows 10, I find that the lack of placeholders is a serious issue. And like many others, it really inhibits my desire to use this new OS version.