response times discrepancies using -q and -d Vs -Q

[felix-ns1]

I'm observing large discrepancies in response times when using flamethrower with -q -d vs -Q, in what seems to be equivalent parameters:

-q 15 -d 1000 -c 100 vs -Q 1500 -c 100
~1500 QPS for both cases
30ms vs 4ms average response times respectively.

Test setup:

• digital ocean droplet host: 8cpu/16gb RAM (CPU-Optimized)
• running dns in authoritative mode
• Single zone with single A record testrecord.example.com
• Flamethrower commands
  a) docker run --rm ns1labs/flame 10.118.0.3 -q 15 -d 1000 -c 100 -r testrecord.example.com -T A -o test-a.json -v 4 -l 60
  b) docker run --rm ns1labs/flame 10.118.0.3 -Q 1500 -c 100 -r testrecord.example.com -T A -o test-b.json -v 4 -l 60

Results:

-q 15 -d 1000 -c 100                   -Q 1500 -c 100
--------------------                   --------------
run id      : 7fff24010170             : 7ffe0393aad0
run start   : 2021-09-01T18:02:49Z     : 2021-09-01T18:05:57Z
runtime     : 62.8054 s                : 59.7964 s
total sent  : 90000                    : 89600
total rcvd  : 86597                    : 89600
min resp    : 9.42086 ms               : 1.05053 ms
avg resp    : 30.8278 ms               : 3.9897 ms
max resp    : 58.0175 ms               : 31.3559 ms
avg r qps   : 1431                     : 1477
avg s qps   : 1500                     : 1477
avg pkt     : 51 bytes                 : 51 bytes
tcp conn.   : 0                        : 0
timeouts    : 3403 (3.78111%)          : 0 (0%) 
bad recv    : 0                        : 0
net errors  : 0                        : 0
responses   : NOERROR: 86597           : NOERROR: 89600

Is this possibly a bug?