Performance

On what kind of hardware (and OS) are you running Ubooquity ?

Running on debian/WD mybooklive Nas. Maybe a index on the database with the sorted order. 

A missing index has been added in Ubooquity 1.5.0.
So if you are running with this version, you already have the index.
By the way if you are adventurous and like SQL, exploring the database only requires the H2 jar and some tutorial reading.

I'll try to generate a big library (20k books is quite a collection) and do some tests on my Raspberry Pi (which should be less powerful than your NAS), but it will take time.