A database is OK if you want to access existing data quickly.
MP3tag is a program that helps to create the data by adding tags to the files.
Ususally, I apply MP3tag to tag new files which are not in the database. So I would have to update the database first before I can see the new files. I don't see much of an advantage in such proceedings.
And, after one has updated the files, it would be necessary to also update the database. In which intervals would you like to do that? After each update or after the end of session?
So, yes, if you cannot be sure that your data is somehow uptodate and you have to load all the files every time, this can be a tiring affair.
This would then probably take just as long as loading the files in the first place.
I agree with poster poster that you do not have to load all files.
You can drag&drop a selection of files and folders into MP3tag to deal just with these files.