Very long restart time on Debian 10

name: Bug report
about: Very long restart time on Debian 10

Describe the bug Restarting the isc-dhcp-server takes over 2s (average 2.1s) on a strong host system with a very minimal config

To Reproduce Steps to reproduce the behavior:

Run time service isc-dhcp-server restart

Expected behavior A reasonable fast restart time

Environment:

ISC DHCP version: 4.4.1
OS: Debian 10 64bit

Additional Information
dhcpd.conf

subnet xxx.xxx.xxx.0 netmask 255.255.255.0 {
range xxx.xxx.xxx.2 xxx.xxx.xxx.128;
}
include "/etc/dhcp/vm.d/xxx.xxx.xxx.44.conf";

xxx.xxx.xxx.44.conf

host h1 {
filename "URL";
hardware ethernet <MAC>;
option routers <ROUTER>;
option subnet-mask 255.255.255.128;
fixed-address <IP>;
option domain-name-servers 1.1.1.1,1.0.0.1;
}