Connect time to postgresql on my Win 10 machine incredible slow. It take 2.5-3.5 seconds for a connect.
$ time 'c:/Program Files/PostgreSQL/10/bin/psql.exe' -h 127.0.0.1 -p 5433 -U xxx -c 'select true' bool ------ t (1 row) real 0m3.416s user 0m0.015s sys 0m0.000s
Same time when i try to use psycopg2 python driver. Same time for postgresql version 9 and 10. On the other hand connect time to mysql is 0.002, issue only with postgresql.
Here relevant logs with max debug from postgresql
2018-03-19 21:24:43.654 +03  DEBUG: 00000: forked new backend, pid=21268 socket=5072 2018-03-19 21:24:43.654 +03  LOCATION: BackendStartup, postmaster.c:4099 2018-03-19 21:24:45.248 +03  LOG: 00000: connection received: host=127.0.0.1 port=9897
It fork new backend and then only 2 seconds later logs connection received
UPD Even if i manage to avoid connection delay of postgresql ( for example via pgbouncer, or if postgresql running in docker) request still take 1.3-2seconds, but from first sent package till last its only 0.022 second, all other time idk what happening but not a network communication between client and server. Same code if run within docker - 0.025 second. From windows - 1.3-2sec but network interaction only 0.022sec
There actually two problems that might be caused by same thing or different, no idea.
Postgresql not sending packet for 1.8 second for unknown reason
Even if first problem eliminated and network interaction down to 0.022 sec whole thing still take 1.3-2 sec instead of 2.5-3.5 ( using either psql or psycopg2)