There are a few tricks that speeds the conversion up.
For starters, i've noticed that it goes way faster if you just leave the comp when doing it. Compared to when you are for example, browsing, downloading etc.
Also, with the latest BatchDPG ppl seem to prefer to use the profile High/Ultra setting. Which takes a longer time to convert but makes the size smaller something. But I prefer using the profile Med which I actually notice very little difference in quality and size. But most importantly, with the Med profile, the conversion goes about 50-75% faster than using the High/Ultra Profile.