It is not problem with the Zortam (ZMLIMD) database speed. Connection to Zortam database takes less then a sec., but it takes some time to write ID3 tags specially if it saves picture tags or if ID3v2 tags don’t exist at all.
Once the tags are written to Mp3 Id3v2 tags it takes less time to update tags.
CDDB is used when if you wish to convert a CD to Mp3 or any other music format, and can not be used for auto tagging,
Why CDDB can not be used for auto tagging?
CDDB identifies CDs with a 32-bit number which contains CD disk id and can not be used for auto tagging except for current CD disc. CDDB also doesn’t have lyrics and cover arts in CDDB database.
That’s the reason why Zortam came up with Zortam Multi language Internet Music Database (ZMLIMD).
From ZMLIMD you can get all information (including lyrics and cover arts), all that you need is artist and song name.