BUG #15712: latency delay for first query execution in PostgreSQL DB 11

The following bug has been logged on the website:

Bug reference: 15712
Logged by: Sandeep Kumar
Email address: sandeep(dot)t(dot)kumar(at)gmail(dot)com
PostgreSQL version: 11.0
Operating system: Windows
Description:

Delay of query execution due to latency on PostgreSQL DB 11 and this is
happening for first query execution and rest of queries going smooth.

Following are the test result from JMeter with 5 concurrent users , please
observed the Latency for first 5.

Start time Thread Label Sampletime
Bytes Latency Connect time(ms)
=========================================================================
1 04:15:43.473 Postgres 1-1 SQL1_PG 73 Success 58544 1 0
2 04:15:43.673 Postgres 1-2 SQL1_PG 357 Success 58544 166 0
3 04:15:43.874 Postgres 1-3 SQL1_PG 362 Success 58544 156 0
4 04:15:44.075 Postgres 1-4 SQL1_PG 365 Success 58544 161 0
5 04:15:44.275 Postgres 1-5 SQL1_PG 236 Success 58544 165 0
6 04:15:43.546 Postgres 1-1 SQL2_PG 138 Success 40336 0 0
7 04:15:44.929 Postgres 1-1 SQL3_PG 324 Success 165650 0 0
8 04:15:44.031 Postgres 1-2 SQL2_PG 1266 Success 40336 0 0
9 04:15:45.298 Postgres 1-2 SQL3_PG 325 Success 165650 0 0
10 04:15:44.236 Postgres 1-3 SQL2_PG 1415 Success 40336 0 0
11 04:15:44.440 Postgres 1-4 SQL2_PG 1269 Success 40336 0 0
12 04:15:44.512 Postgres 1-5 SQL2_PG 1269 Success 40336 0 0
13 04:15:45.651 Postgres 1-3 SQL3_PG 353 Success 165650 0 0
14 04:15:45.709 Postgres 1-4 SQL3_PG 339 Success 165650 1 0
15 04:15:45.781 Postgres 1-5 SQL3_PG 325 Success 165650 1 0
16 04:15:45.254 Postgres 1-1 SQL4_PG 999 Success 15935 0 0
17 04:15:46.254 Postgres 1-1 SQL5_PG 174 Success 23208 0 0
18 04:15:45.623 Postgres 1-2 SQL4_PG 948 Success 15935 0 0
19 04:15:46.572 Postgres 1-2 SQL5_PG 169 Success 23208 0 0
20 04:15:46.005 Postgres 1-3 SQL4_PG 1018 Success 15935 0 0
21 04:15:46.107 Postgres 1-5 SQL4_PG 916 Success 15935 0 0
22 04:15:46.049 Postgres 1-4 SQL4_PG 985 Success 15935 0 0
23 04:15:47.023 Postgres 1-3 SQL5_PG 212 Success 23208 0 0
24 04:15:47.035 Postgres 1-4 SQL5_PG 200 Success 23208 0 0
25 04:15:47.024 Postgres 1-5 SQL5_PG 211 Success 23208 0 0