I've just noticed that my CPU graphs have frequent spikes growing throughout each day.
They stop at midnight, and can be seen growing from about 3am until they hit 100% around 11am, and remain at 100% through the day.
Also, when I run 'top', I frequently find postgres running at 100% for exactly 5 minutes, before being recycled(?) to a new process, which immediately drops to 0% CPU.
The postgres processes may be related to webmin use, but I am unable to consistently reproduce it, and I am staying out of the accounting pages (which are slow for me).
Barry