That's not quite what I was asking.
In Roxio (at least in 7.5 & below) you can specify whether to cache or not. Caching here means copying the whole of the CD/DVD to the HDD first & then starting the burn once this is done.
You choose this option if the reader device is not fast enough to keep up with then selected burn speed of the target.
Also if the source & target are on the same IDE channel you'll probably be best to select this option.
I suspect this is what you need to look at.