UTM 115w - High CPU usage on syslog-ng - why?


I recently discovered that my UTM 115w at home (which means serving only 1-2 users) is permanently running at around 66% CPU load for over a year now. The reason is the syslog-ng deamon. On Tuesday I installed a firmware-update and after the reboot it stopped for two days. Can somebody tell me what's going on here?

Thanks in advance,