I got frustrated with list management performance issues in the main 2.1.3 release.
I used homebrew to install most recent python, and used pip3 to install most recent version of picard. I had to manually homebrew install gettext.
Suddenly, unexpectedly, picard is responsive even when loading thousands of tracks in dozens of albums.
This is not itself a bug, but may be a clue to help debug performance issues when loading large numbers of tracks.