Was this a switch from REkordbox 5 to 6? If yes, it takes a while indeed.
Analysis in general takes time, especially if you haven't toggled the setting to use multi core.
The analysis data, cues, loops get saved to the Rekordbox database. None of this information is saved to the music file, like Serato does.
It is recommend to make backups often. Then when you move to a new computer or install a new OS you only need to restore the backup. And make sure the files are in the same folder structure as before. Or you point the relocate function to the folder to search in.