I have an update. I uninstalled and reinstalled VMware Tools and the problem persisted. On a whim, I tried to transfer a large .zip file on to the Desktop of the Windows VM. That worked and the transfer was really fast.
If I try to transfer to within my OneDrive folder, then it's really, really slow. So, that's the difference. As long as I'm transferring to a folder that's not synced, the transfer works fine.