tomrevam <tomer(at)fabrix(dot)tv> writes:
> I set synchronous_commit to off and expected trivial inserts (single row,
> 6-8 columns) to always return quickly. However, I see that during
> checkpoints they sometimes take over a second.
What sort of disk hardware have you got? It sounds overstressed.
It might help to increase wal_buffers.
regards, tom lane