I searched the forum and found some information about using PerfectTunes' Album Art with a NAS and how it needs access to the files and why it can take a long time but I didn't see any information relating to my question.

I just purchased it recently to play with the Album Art and wanted to know if it scans the folder in its entirety every time I open and use Album Art or does it save/cache directories so that it starts up quicker next time?

For example, if I pause/stop it at 10% to work on albums, on the next startup does it start scanning at 10% or does it start again from the beginning? If it picks up where it left off I could work on the library in piecemeal, if it doesn't I guess I need to wait for it to complete.

Is waiting the recommended practice or is it suggested to copy/move small sections to the local drive, work on those then move them back and rinse and repeat?