This has been suggested before by others, but it's a major annoyance for me.
I have a VERY large music collection, so starting MP3TAG takes as long as a cup of coffee for me.
Can at least the "Favorite Folder" have change tracking added?
It's very simple to implement - MP3TAG could keep a small file containing file name, last known modified date for that file, and maybe a checksum for the file. On startup, all MP3TAG would then do is compare the folder contents with this data to see which files it has to re-scan. MUCH faster than re-scanning every file of thousands.