OK, if it scans the prints so you get usable results that's good. You don't say how long it took to scan - I suppose - the whole page of images - or just one image? And what size, and what resolution? What computer set-up are you using? All these things affect scan speed, as does your computer and software. So to benchmark your question, I did a few experiments that may be useful guidance for you. For reflective scans (flatbed of prints - your case) I use an Epson Perfection V750 Pro, connected to my MacPro OSX 10.6.8 by USB 2.0. I use SilverFast Ai8 Studio for scanning - as far as I could tell, not available for your scanner model, but Vuescan will work with your scanner. Anyhow, that's my set-up used for this benchmarking.
Unfortunately I don't have any hard figures on how long the scans took but, bearing in mind there was a fair bit of faffing about and experimenting with some settings in Vuescan to begin with, I got eight images scanned in around two hours, although I think I had the multi-pass scanning setting on in Vuescan which I could probably have taken off (as I'm not sure if it improves things much compared to using it on slides or negatives)
This was one image at a time as so far the album I've scanned from is a mix of snaps from over several years so there's no consistency to the images. This has meant I found I needed to apply the "Restore Fading" colour filter in Vuescan for some of the pictures (in truth I'm not sure if they faded or there was some issue with however they were shot but the results didn't quite look natural).
The scans were at 600dpi and 48-bit mode (and as I said, I think I had the multi-pass scanning enabled)
The main thing I noticed is that the scanner hesitated a bit periodically - this happens when data transmission isn't keeping-up with scanner speed. I think this is a USB-2 limitation, and if so with USB-1 the stalling and scanning time would be hugely greater.
I don't recall noticing any stutter but then the prints I've been scanning in so far aren't particularly big - a lot of the older photos (pre-80s) I saw while flicking through one album appear to be smaller than 6x4, some of those that I think are from the 40s and 50s don't appear to be more than about 4" square
-what kind of output do you need, hence what image size and resolution is needed?
That's kind of the $64,000 question. So far I've scanned in using the A3 Printed Size option (although I've always been a bit hazy on the purpose of that setting as I'd have thought the printed size would be something the photo package would scale the image for should it be insufficient) from the Output tab in Vuescan but to be honest I'm not sure whether these will actually ever be printed or not, it's more a case of archiving digitally in the best possible quality in case mum's house should burn down and I don't have the prints to go back to.
-what is the computer processing environment?
Computer processing environment is a Lenovo Windows 7 (64bit) laptop, 4GB RAM (will be moving up to 8GB once I've finished giving it a "shake-down"), i5-3210 (2.5Ghz)
For the time being any editing of the images will likely be done in my ancient copy of Photoshop Elements (unless GIMP ever gets decent controls sometime in the near future)
-subjective issue: how much time is "too much" to get from pushing the scan button to the final result you want, including post-scan workflow if any.
Given that I'm purely looking at scanning in right now, so no post-scan workflow to consider, ideally no more than a couple of minutes