iTunes 12.7 slow to add new music in Windows 10

Hi,

I'm running iTunes 12.7.4.80 -- the latest update as of this writing.

After recently upgrading my Microsoft Surface Pro 3 to Windows 10 (and never having any issues on Windows 8.1), adding new files to iTunes has been unbearably slow.

I've tried all troubleshooting and checked preferences, and cannot resolve the issue. Seeing that this is only a new problem after simultaneously upgrading my operating system AND iTunes, I believe it must be one or the other causing this problem.

My library has close to 60k songs, all of which reside on an external hard drive.

Just this morning, I added about 175 new songs by dragging them from windows file explorer into iTunes, and it took over 5 hours for them to load. While they are importing, and then "processing", iTunes is frozen.

Please help!!!

Thank you.