Are you monitoring the device with Operations Manager? OM executes certain commands to pull data about a vFiler.
If you have lots of volumes or snapshots assigned to the vFiler, and you have frequent polling the vFiler will seem like its constantly processing a command.
If this is the case the best way around this I've found is to manually remove all the volumes from the vFiler (instead of letting the vFiler destroy process return the volumes to vFiler0) then wait for about an hour and try the vFiler destroy process again.
Just ran into this. Make sure that you terminate any cifs services in the vfiler context, then stop the vfiler and destroy it. For some reason it was still polling the DCs for domain access even though the vfiler was stopped in my case.
I had this problem also but this time i was unable to create a DR vfiler after DR work. We had to DR , we recovered and then we have to " vfiler dr resync " but unknown to me i had an session open on the SP and also in the system console , and in the vfiler context. I went back into the SP did a vfiler context vfiler0. Exited and then i was able to perform vfiler dr resync and it worked a treat :0)