Good point about the "slight" wording, though I don't necessary agree that it can get much worse than 2x, with actual workload that: - could be more I/O bound

Good point about the "slight" wording, though I don't necessary agree that it can get much worse than 2x, with actual workload that: - could be more I/O bound than when just doing PK lookups with pgbench - could be getting a wrong plan from the query plan cache if named prepared statement is used