Question Windows 10 File Explorer getting slower... "working on it"


Mar 6, 2019
I've got Windows 10, updated to latest release on a very fast I7, MSI motherboard, NVME boot drive and 4TB Hitachi HDD for data.
Recently, File Explorer on my computer has become slower and slower...and slower.
Opening new File Explorer windows used to be instant so I could browse the contents, or type a few characters to quickly navigate to a file or folder. (ie typing "Fin" quickly gets me to my Finances folder.
Now, when I open a new window, I'll often see "working on it" and it takes from 1 to 15 seconds to open. Typing characters like "Fin" will take me to the first "F" folder...then switch to the first "I" folder...then switch to the first "N" folder...and so on...with about a 5 second delay between each one.
Sometimes the location bar (where it shows ">This PC < Data (D: )> Finances" will be smaller, and filled with overlapping characters or have a black background, making the path unreadable.
The problem seems to go away temporarily after reboot, but returns after running for a few hours.
Is this a Windows problem? A data drive problem?
I'd love to get this fixed, as I really don't want to buy a new boot drive and reinstall Windows.
Any ideas or advice?