I am bitten by this, scanning takes 25-30minutes.
I started googling and came to this forum and the numerous threads with users complaining and devs saying "we have to do it this way, buy CC if you don't like it".
I would just like to point out we DON'T have to do it this way. Yes using full file system enumeration is the way almost all applications use MTP, but that is not how windows explorer does it. And as of the past few months we have been cluing into this. First with a proof of concept from google
https://github.com/hanwen/go-mtpfs/, and then a nice fork of gfvs from Phillip
https://github.com/philipl/gvfs. And that is just what I found in 5 minutes.
I don't know if this will change how MTP is implemented, but on-demand file enumeration is not hard. I'm just tired of seeing the same excuse/statement.
Also why can't we set ignores for the data after the fact? Calibre is showing everything from app data in /storage/sdcard0/Android/data to crap in /storage/sdcard0/bugreports as ebooks. And it's really annoying. We already default to "Calibre_Companion, Books, eBooks/import, eBooks, wordplayer/calibretransfer, sdcard/ebooks, kindle", if we find one of those directories why are we displaying EVERYTHING else on top of it?