Related to FL-9499 i saw that dhclient is more fast that dhcpcd client but FWIS the two packages lag on support dhclient.

1) It seems that sys-apps/corenetwork and net-misc/ifrc supply both /etc/init.d/net.lo

 🚧  warningfile conflict found file conflict between 'sys-apps/corenetwork-1.6.5+3' and 'net-misc/netifrc-0.6.1' ( file: etc/init.d/net.lo )

I think that here is better take the file from sys-apps/corenetwork and maybe set corenetwork as dependency of net-misc/netifrc?

2) the package net-misc/ifrc supply the file /etc/netif.d/dhclient but it calls dhcpcd instead! Just replacing the daemon binary with dhclient path inside the file /etc/netif.d/dhclient works but maybe must be improved the integration.

Hereinafter, the result:

>>> [test-boot] - wait=true ; timems=$(date +%s%3N) ; while ${wait} ; do withip=$(ip r list | grep "dev eth0" | wc -l) ; if [ "${withip}" = "0" ] ; then sleep 0.001 ; else wait=false ; fi ; done ; endtimems=$(date +%s%3N) ; ms=$((endtimems-timems)) ; echo "Time to get ip (ms): ${ms}" ; if [ -z "${skippoweroff}" ] ; then poweroff ; fi
 - ☕ 
Time to get ip (ms): 4
All done.
 

My suggestion is to use dhclient in container world for sure by default.