Обсуждение: [PERFORM] performance contradiction

I have two servers. On the first one I have postgresql version 9.6 . On the second one I have version 9.3 . I ran pgbench on both servers.

First server results:

scaling factor: 10

query mode: simple

number of clients: 1

number of threads: 1

duration: 10 s

number of transactions actually processed: 4639

latency average = 2.156 ms

tps = 463.818971 (including connections establishing)

tps = 464.017489 (excluding connections establishing)

Second server results:

scaling factor: 10

query mode: simple

number of clients: 1

number of threads: 1

duration: 10 s

number of transactions actually processed: 3771

tps = 377.084162 (including connections establishing)

tps = 377.134546 (excluding connections establishing)

So first server perform much better.

BUT if I run a trivial select on both servers, on a similar table, the select perform much much better on second server!

First server explain results:

Limit  (cost=0.00..0.83 rows=30 width=33) (actual time=0.152..0.794 rows=30 loops=1)

  Buffers: shared hit=1

  ->  Seq Scan on symbols_tests  (cost=0.00..1.57 rows=57 width=33) (actual time=0.040..0.261 rows=30 loops=1)

        Buffers: shared hit=1

Planning time: 0.282 ms

Execution time: 1.062 ms

Second server explain results:

Limit  (cost=0.00..0.83 rows=30 width=622) (actual time=0.006..0.010 rows=30 loops=1)

  Buffers: shared hit=1

  ->  Seq Scan on symbols_tests  (cost=0.00..1.57 rows=57 width=622) (actual time=0.006..0.007 rows=30 loops=1)

        Buffers: shared hit=1

Total runtime: 0.020 ms

Both servers have SSD. First server is a VPS, the second server is a dedicated server.

Any idea why this contradiction ? If you need more details regarding server resources(CPU, memory etc) please let me know.

Regards