Move DocLib with 1,500,000 items, fastest methods?

I had a document library explode in size. I need to move it to its own content db. Later, we'll figure out how to manage it better.

The documents are small emails with metadata extracted into sharepoint columns.

What I've tried so far is an export/import:

• Export-SPWeb "http://intranet/it/" -Item "emailLibrary" -Path "X:\emailLibrary" -NoFileCompression -IncludeUserSecurity -IncludeVersions All
• Create DB: emailLibrary_Content
• New-SPSite -url http://intranet/sites/emailLibrary -ownerAlias "domain\user5" -contentdatabase "emailLbrary_Content" -template "STS#1" -Name "emailLibrary"
• Import-SPWeb "http://intranet/it/" -Path "X:\emailLibrary" -NoFileCompression -IncludeUserSecurity

This has been running for almost a week now, and is just over 80% complete. There has to be a better way.

I've since tried:

• Export List to Excel, save the iqy as xslx, create new library based on xslx. When I try to open the .iqy on my machine to save as xslx, I'm getting "You do not have permission to view the entire list because it is larger than the list view threshold enforced by the administrator." Yes, I could increase the list view threshold.
• Explorer View: Create new library, copy folders/items over manually. Got a "Preparing to copy" window, which would disappear after around 30 seconds without anything copied to the new library.

Any better courses of action?

Much thanks,

Scott