I can get one converted in less than 2 hours, but it does mean dedicating the PC to that one process only, so not realy valid for most, when using an all-in-one converter burning software.
I use dedicated progs for the work now, encoder, author and burning, and the time is realy dependant on the quality of the original file, and the setting you use. Some take less than 2 hours some take more so I would say as chef does 2 hours isn't bad at all.
The tip I would give is set it up before you go out or to bed and then it will be ready for you when you get back or up. It's how I do it all now.