I am using a Rock 4C+ running Debian 11. It takes about 25 seconds from power-up until my application program is started by cron. This seems excessive to me. I have looked at guides on the Internet and followed some of the suggestions for deleting services. None of this makes much difference. I have been using systemd-analyze to identify services to delete. For instance, the postfix@- service looked to be a good candidate for removal. However, disabling it made no difference to the boot time.
I have also tried changing from the graphical target to the multi-user target. The application doesn’t require either a graphical or a console interface. However, the choice of target doesn’t seem to influence the boot time either.
Could anyone suggest an approach for optimising the boot time. Would starting my application as a service make any difference?