dumpdb take 12+ seconds to complete.

cacheclean system test failed because dumpdb took excessive time to complete.

I:cacheclean:check the number of cached records remaining (13)
I:cacheclean:timed out waiting for 'rndc dumpdb' to finish
Can't open ns2/named_dump.db.test13: No such file or directory.
I:cacheclean:found 0 records expected 1
I:cacheclean:failed

21-May-2020 04:21:38.807 received control channel command 'dumpdb -cache _default'
21-May-2020 04:21:38.807 dumpdb started: -cache
21-May-2020 04:21:38.807 delete_node(): 0x7febb871ad68 second1.top1.flushtest.example (bucket 94)
21-May-2020 04:21:38.807 delete_node(): 0x7febb871fc20 top2.flushtest.example (bucket 0)
21-May-2020 04:21:38.807 delete_node(): 0x7feb4fe51bd0 second1.top3.flushtest.example (bucket 36)
21-May-2020 04:21:38.807 delete_node(): 0x7febb871aa38 second2.top3.flushtest.example (bucket 0)
21-May-2020 04:21:48.887 socket 0x7febb8801600: internal_accept called, locked socket
21-May-2020 04:21:48.887 socket 0x7febb8801600 10.53.0.1#38867: accepted connection, new socket 0x7febb83e8310
21-May-2020 04:21:50.555 expiring v4 for name 0x7febb858f270
21-May-2020 04:21:50.675 killing name 0x7febb858f270
21-May-2020 04:21:50.675 ENTER clean_finds_at_name, name 0x7febb858f270, evtype 0004000d, addrs 00000003
21-May-2020 04:21:50.675 EXIT clean_finds_at_name, name 0x7febb858f270
21-May-2020 04:21:50.687 dumpdb complete