If Midnight Commander needs several seconds to startup, check the interfaces line in your smb.conf. According to this page, the built-in Samba code of mc is outdated and doesn’t recognize device names like eth0 or lo as the newer smbclient does. So it tries to resolve those into IPs which takes ages until they time out.

Replace the devices by their respective netmasks (e.g. 192.168.1.0/24) and mc will startup instantly.