Performance penalty when requesting text values in binary format

I'm the creator of the PostgreSQL driver pgx (https://github.com/jackc/pgx)
for the Go language. I have found significant performance advantages to
using the extended protocol and binary format values -- in particular for
types such as timestamptz.

However, I was recently very surprised to find that it is significantly
slower to select a text type value in the binary format. For an example
case of selecting 1,000 rows each with 5 text columns of 16 bytes each the
application time from sending the query to having received the entire
response is approximately 16% slower. Here is a link to the test benchmark:
https://github.com/jackc/pg_text_binary_bench

Given that the text and binary formats for the text type are identical I
would not have expected any performance differences.

My C is rusty and my knowledge of the PG server internals is minimal but
the performance difference appears to be that function textsend creates an
extra copy where textout simply returns a pointer to the existing data.
This seems to be superfluous.

I can work around this by specifying the format per result column instead
of specifying binary for all but this performance bug / anomaly seemed
worth reporting.

Jack