The above 128GB run game me some good insight into where costs were going, as it wasn't fully thrashing as with the mini. At about 800k almost 50% of time during validation was spent on the single query to obtain potential double spends (which we never actually encounter), in the point table. As the table contains 40 bytes per input, it grows to about 100GB, and table heads take about 16 GB, leaving only 12GB for block and previous output query and validation.
(edited)