MBS-8720 was supposed to make this faster, and I guess it did, but it's still extremely slow. https://gist.github.com/mwiencek/7cdd04e18c343bca16d97ffc2b8b1929

Changing a_ins_edit_note to not insert rows where edit.editor = edit_note.editor means we can get rid of the filter in Data::EditNote::find_by_recipient, nearly cutting the query time in half from what I observed. But that's even before deleting all the existing rows where that condition is true (count = 20885520). So I guess we should start there.