Well I am under the assumption (perhaps incorrectly) that MB is creating lists for artists, albums, tracks, etc as the information is parsed from the files.
That is how it works indeed.
If you start with Musicbee (or any other media player), you point it to the root of your music collection and it will scan all the files, read all the tags and store it in its own database. This is very time consuming but when done, all it has to do is keeping its database in sync with the files.
Obvious, querying a database is much faster than reading all audio files. This explains why the response of Musicbee is crisp. You are not accessing individual files, you are querying a database.
Musicbee goes one step further, is caches the database to get an even better performance.
Windows does the same, it creates a database of all the files. Just open de Windows File Explorer. How could it be so crisp? Indeed it queries a database instead of scanning all the files on a disc.
On startup Musicbee only have to compare the date last modified in its own database with the date last modified in the database of the file system. Only if there are differences, it has to do something.
