NAS542 with terrible response time after firmware update to V5.21(ABAG.1)

Reinhold

Today my NAS542 updated to firmware V5.21(ABAG.1). Now it is terrible slow. Accessing files on the system is almost impossible. It sound like there is constant activity on the disks.
Processor started with 100% busy, now, after 10 minutes is down to about 40 % which is still unusual.
Any ideas, what to do?
Thanks
Reinhold

#NAS_Oct_2018

Reinhold

Hm, to check for other reasons, I've restarted the whole network (HUB and WLAN hardware). Looks liek the problem is gone.