in the last post, I have tried additional pgbench runs for "synchronous_commit = off" and "fsync = off".
The results are shown in the right pic.
It shows that "sync_commit = off" and "fsync = off" are almost the same, and these are faster as much as "UNLOGGED", except a tiny behind.
I think the tiny behind means the difference between "sync_commit = off (or fsync = off)" and "UNLOGGED" that the WAL records would be eventually written, or not.
"UNLOGGED" table allows DBA to make some choices on the "Performance-Consistency" trade-off for each table.
"synchronous_commit = off" also allows it for each transaction, and "fsync = off" allows it for a whole database cluster.
These really look like, except the UNLOGGED table must be truncated on the crash recovery.
Robert Haas: Global Temporary and Unlogged Tables