Query returning many rows consumes two cores on MacBook Pro

## What did you do?

I ran a query that returned tens to hundreds of billions of rows.

## What did you expect to happen?

I honestly don't know what I expected to happen. I'm… sorry? 😂

## What actually happened?

The rows counter updates very quickly, rather like #610. Could use similar throttling? But this is more extreme CPU utilisation… and rapid growth in compressed RAM utilisation. I can't imagine you're loading data directly into the UI, right? Anyway, this was very silly behaviour on my part more than Postico's.

## What software versions are you using?

Postico version: Version 1.4.4 (3963)

macOS version: 10.14.1 (18B75)

PostgreSQL version: PostgreSQL 8.0.2 on i686-pc-linux-gnu, compiled by GCC gcc (GCC) 3.4.2 20041017 (Red Hat 3.4.2-6.fc3), Redshift 1.0.4896

No files, tests, or entry points are identified in the issue. Start by reviewing the handling of queries that return extremely large result sets and the row-counter behavior referenced in issue #610; clarify the intended throttling and memory-usage behavior before defining done.

Written by the indexing model from the issue text.