Question on shredding a terebyte drive

[Dean S. Messing]

I have a terebyte sata drive that I need to securely wipe clean.  It
originally had 2 partitions.  I deleted them using `fdisk', rebooted,
and then as root ran

    shred -vz /dev/sdd

The drive is capable of about 60MB/sec, but shred is only "shredding"
about 25MB every 5 seconds according to its output.  Since the default
number of passes is 25, this works out to about 5 days.

The `shred' process is running at 100% CPU, presumably computing
the special random patterns for erasure.  Since I have 4 CPUs
would creating 4 unformatted partions on the drive and then running
something like:

   shred -vz /dev/sdd1
   shred -vz /dev/sdd2
   shred -vz /dev/sdd3
   shred -vz /dev/sdd4

in parallel cut my time?  Would be just as secure?

Thanks
Dean