Re: V3 protocol is slower than V2

ITAGAKI Takahiro <itagaki.takahiro@oss.ntt.co.jp> writes:
>   [V2]  PQsendQuery (V2; original)
>   [V3]  PQsendQueryParams (V3)
>   [V3P] PQsendQueryPrepared (V3 with prepared statements)

> V3 was 12% slower than V2, and V3P was 40% faster than V2.

Those aren't really comparable, because the functionality is different.
Did you check plain PQSendQuery on both V2 and V3?
        regards, tom lane