When using scheduler.addCron (vs scheduler.addJob) it appears that the scheduler will start the job multiple times at once (think 20-400 times).
This happens even with removing the cron at the start of the called method and re-adding it at the end.
Attached code exemplifies the differences.
This was effectively bringing a few of our servers to their knees, so anyone experiencing performance degradation when using crons, may be experiencing this.
Reported at https://support.servoy.com/browse/SVY-2067