I just upgraded my QNAP TVS 462 from 4.2 to 4.3.3.0154 and now the NAS was running high CPU between 85 & 99% for several hours.
After disabling container station, virtualization station and all other services I discovered that disabling the "file service for Microsoft Networking" made the CPU back to less than 20%.
I need to connect to my NAS using SFTP from my linux boxes, not really a problem.
I will open a ticket to QNAP support.
Any News? I got the same issue...