Bugzilla – Bug 105922
cron runs the first time the system is started, slowing down the system tremendously
Last modified: 2005-08-22 11:01:08 UTC
The first time the system runs, it executes all of the cron jobs, at least the ones in cron.daily. This means things like the beagle index builder, the mandb updater, and (if you installed it) updatedb run, which put a tremendous IO burden on the system. It would be best if these ran in the middle of the night as they are supposed to.
they are not supposed to run at a fixed time. Just once daily. It is on purpose that these run 15 minutes after boot (run-crons from /etc/crontab). If you want to have them run at a fixed time you should use /etc/crontab not the directorys...