Systemd

More articles on systemd at CentOS 8.x systemd or systemctl

Newer versions of RPM based OS use systemd for service start/stop and enable/disable on startup

Check service start-up time

Systemd makes it very easy to analyse which service is taking how much time during boot. To do this use:

systemd-analyze blame > blame.txt

and then read various service start-up times from blame.txt file.