Slow converting HD video footage

I usually take video footage from my non-HD Mini-DV camcorder edit it through Video Studio X4 and burn it to ISO file or straight to DVD disk. 1 hours footage usually takes approx. 45 minutes to render on my PC.

Borrowed my dads HD camcorder and tried to do the same using VS X4, i.e burn to DVD disk or output to Blue Ray Video Folder on my HDD. Trouble is the render time has leapt from 45 mins with the Mini-DV footage to an estimated 10 hours with the HD footage.

What can I do or buy to drastically reduce this render time, or is this the norm with HD footage?

Thanks,

Chris