I would like to have a progress bar that shows that something is happening when cleaning metadata. I would like it even more if it displayed some information about how much was done and how much remains to be done.
There should be two progress bars. One for each file being cleaned, and one global progress bar. For example, there could be a progress bar of each file, kind of like if the file was being downloaded. And a global indicator that shows how much files still need to be cleaned (e.g. "35% done" or "12/42").
(from redmine: created on 2014-07-18, closed on 2015-08-21, relates #7684)