[vanusa]

Most of that time is spent executing poorly crafted Oracle SQL queries drawing millions of rows into the analytical run-time for, sorting, aggregation, discarding, merging, and spliting tasks.

Depending on what goes on in between the lines of all that "sorting, aggregation, discarding, merging, and splitting" -- the core guts of what you're doing might quite easily done within Postgres.

And 81 million rows? That will fit on your laptop, easy (especially if many are discarded in the early stages of processing).

Or it perhaps might not fit so easily. But the basic point I'm trying to make here is: don't be afraid of simplicity. All other unknowns being equal, it's as good a starting point as any.