and back to the original question, the first time you defrag will obviously take longer then any subsequent, unless you wait a long time again.
normal defrag takes much less time then file optimizing, so perfect disc will take longer then then any utility that just defrags.
I like the function the perfectdisc performs, and I believe you get as much benefit in ntfs with the files layed out contigously as you get from defragging the files.
now, of course if there;s no information in your disk, the size dosn't matter.
but, neither does the amount of files on the disk...if the disc is full, but contigous, then that will take no time at all to defrag.
the amount of time it takes to defrag is a factor of how contiguos the drive is