hmm... ok.. so your probably running faster than me other than maybe IO unless you have an ssd your running off. I'm about 4 generations older on the cpu and mother board than you are. That 70 meg file size is huge compared to most of the stuff I convert though. I'm usually .5 meg to 2 meg in size. It might actually work out equivalent if you figure roughly a minute per meg
I just sent 40 books to my kindle and 13 needed to be converted to mobi. average file size of about .5 meg.. conversion and transfer started at 12:32 and ended at 12:43 for a run time of 11 minutes. The job que showed that each conversion took about 20 seconds. I think the send to device job ran parallel to the conversions, jumping back and forth. I will have to keep a closer eye on the details and get a better feel for the true speed over the next few weeks. Maybe do some conversion jobs and document them.