journalctl --follow

[Wolfgang S. Rupprecht]

Is journalctl in the tail -f mode called "follow" supposed to be
realtime?  I'm seeing it more or less output log lines in realtime for
many hours and then eventually it falls behind with half an hour or one
hour delay.

The (simplified) lines are from a perl sshd tracker are:

    open( LOG, "journalctl -o short-precise -u sshd --follow |");
    while (<LOG>) {
    ...
    }

I suppose, it is possible that the delay is in perl, but journalctl
seems more likely to be the culprit, hence the subject line.

-wolfgang