from man nfsiod:
nfsiod - local NFS asynchronous I/O server
It is used for client NFS readahead mostly. You don't need it if you are not using NFS, but even so, it is a very small program, mostly in kernel space, and does not use any resources if there is no NFS activity. Apparently, NFS client is started on your machine.
(for UNIX people, nfsiod is known as biod on other NFS implementations)
