Just to add some more data related to this thread.
I have a WD 1TB NAS at home here; it is not gigabit capable and the best transfer rate I get is about 35MB/s
I did some queue timing of 8Mpx jpegs (100% quality).
Individual images could be added to the queue "instantly"; 10 selected took about 0.3 secs per image.
20 and above images selected and added to the queue took much longer for some reason, at about 4 secs per image.
This is still much better than 8 secs per image.
As far as cropping goes, either as an image crop (filter) or a print crop, that was as normal compared to an image on the local hard drive.
Terry