big performance loss in 9.16 compared to version 9.11

Summary

I was doing some test before upgrading from bind 9.11 to 9.16 and I encounter a big perfomance loss between those verions. I have a loss of 75% ! I was at 400k query per second in bind 9.11 and in bind 9.16 i was only at 100k query per second

BIND version used

BIND 9.16.6 (Stable Release) id:25846cf

BIND 9.11.22 (Extended Support Version) id:6a05a96

Steps to reproduce

Use the following named.conf file :

options {
  listen-on-v6 { any; };
  version "";
  max-cache-size 100M;
  max-journal-size 10M;
  check-names master ignore;
  check-integrity no;
  check-sibling no;
  dnssec-secure-to-insecure yes;
  directory "/etc/namedb";
  recursion no;
  server-id "bind-auth";
};
controls {
        inet 127.0.0.1 port 953 allow {
                127.0.0.1/32;
        } ;
};
acl "admin" {
        "any";
};
zone "incache" {
        type master;
        file "incache";
        allow-update { any; };
};

And for the incache zone use the following zone file :

$ORIGIN @
$TTL 86400      ; 1 day
@       IN SOA  bench. root. (
                                6293       ; serial
                                21600      ; refresh (6 hours)
                                3600       ; retry (1 hour)
                                604800     ; expire (1 week)
                                600        ; minimum (10 minutes)
                                )
                        NS      bench
bench           A       10.0.22.24
$TTL 86400      ; 1 day
*                       A       1.1.1.1
*                       AAAA    8888::1111

Then run a dnsperf (using the file in atachement ):

dnsperf -c 2 -l -d file.dnsperf -s $DNS_IP

file.dnsperf

What is the current bug behavior?

In the Curent Stable 9.16 on FreeBSD 11-Stable I have 100k query per second And in the 9.11 on same hardware and same os I have 400k query per second

On a FreeBSD-12 it is better but i still have a performance drop. On current : 9.16 200k query per second : 9.11 100k query per second

What is the expected correct behavior?

I was expecting at least to have the same performance on both versions.

Relevant logs and/or screenshots

DNSPERF on 9.16 : `

[Status] Testing complete (time limit)

Statistics:

  Queries sent:         966633
  Queries completed:    966633 (100.00%)
  Queries lost:         0 (0.00%)

  Response codes:       NOERROR 966633 (100.00%)
  Average packet size:  request 29, response 45
  Run time (s):         10.000892
  Queries per second:   96654.678403

  Average Latency (s):  0.001024 (min 0.000047, max 0.001866)
  Latency StdDev (s):   0.000074

DNSPERF on 9.11 :

[Status] Testing complete (time limit)

Statistics:

  Queries sent:         4144501
  Queries completed:    4144501 (100.00%)
  Queries lost:         0 (0.00%)

  Response codes:       NOERROR 4144501 (100.00%)
  Average packet size:  request 29, response 81
  Run time (s):         10.000196
  Queries per second:   414441.976937

  Average Latency (s):  0.000225 (min 0.000035, max 0.013790)
  Latency StdDev (s):   0.000053