1 track per second? That's really strange, I have just tried to select and delete 9000 tracks from Music > All tracks and it took about 3 minutes.
i.e. 3000 tracks per minute for me.

Could you share a debug log (item 4b here: https://www.mediamonkey.com/forum/viewtopic.php?f=30&t=86643 ) of the deletion process?
Or alternativelly sharing your MM5.DB and indicating in which view/node you are deleting the tracks should help us to replicate the problem and fix.
You can compress the files (RAR/ZIP) and share just link to the files via private message or eSupport ticket.

Thanks!

I'd moved a folder with 9380 tracks out of the MM5 controlled folder. (MM=off)
To remove this track from library, I'd selected all and try to delete them (only from library).
The task takes 1 second for each track, that would result in 2,5 h for all tracks.
Is this a adequate time?