Picard: Best practice to process huge release?

Yesterday I started to process my 150 CDs from Josef Haydn complete works:

It took several hours for Picard to match the 2’393 (clustered) tracks from the left to the right.

How do you process such large releases?
Do you drag & drop CD by CD from left to right?
Do you fingerprint them first?

If you do that for a CD with 14 tracks, the matching needs only a second or two. Why does the same process (with 170 x 14 tracks) needs several hours and not the expected 170 to 340 seconds?