I thought I'd share some further findings that seem to dramatically impact scan times.
I usually keep my tags pretty clean but even after the suggestions I made in post#6841 I was still not getting some of the scan times I've seen quoted in this thread. I've heard people say it takes around 5 mins to scan a 64GB card, well mine was scanning correctly but still took around 30 mins.
Here are the further steps I took to reduce my scan times:
Using Mp3Tag I brought in all the tracks on the 64GB card and removed all but the ARTIST, ALBUM, TRACK NO., TITLE, YEAR and GENRE.
Initially I thought that was it, no other tags to clean, but after some digging around I found that there are extended tags, some what less supported but still locations to store further information about the track.
In Mp3Tag, highlight all your tracks [CTRL+A] in the menu bar, select 'View' and select 'Extended Tags', this brings up an additional box that lists all the other types of tags hidden in your music files. To remove all unwanted tags (again I removed all but the ones listed above), click on a tag and hit the red cross (it should now say'<blank>'), then select the next tag you want to remove and hit the cross again. Work your way down the list and repeat as needed, but be careful not to delete ones that you want. Once you've repeated this for all unwanted tags simply press okay, and this will automatically prompt the save tags dialog.
Initially I had around 50 extra categories of information buried across my library and I am pretty certain that this added load to the scan process and was the reason for taking so long.
Just to clearly outline what I now have:
Scandisk MicroSD Class 10 64GB card with 2,525 tracks on it, totaling 55.7GB. This is made up of 1,532 flac files totaling 47.9GB and 993 mp3 files totaling 7.8GB.
It used to scan in around 30 mins, I have just scanned it in 5mins 09secs.
One additional point worth noting is that if I changed content on my card and had to rescan it would always freeze. It seemed to be unable to clear the old database/rebuild the new one on top of it. I could only get around this by [volume + and power] factory resetting it and then starting the 30min scan start. Now if I change content on the card it is able to rebuild the new database without requiring me to factory reset.
For those of us that have and still are experiencing freezing or endless scans then I think it's seriously worth looking at the tags of the files. If you have converted your own CD collection then perhaps your library is far less cluttered with unwanted tags but if you download your music (and I'm on about purchased downloads too) then it's worth spending 5 mins to take a look!!