mor einfo would be nice. what filetype are you converting from? what type/speed is your processor? are you multitasking during the process?
when i use nero vision express to convert roughly 3 hours worth of AVI files to dvd it takes around 5 hours (7 or so if I'm multitasking during the process)
that's on a p4 2gHz, 512mb RAM.
there's a lot of work to be done. encoding takes the longest amount of time, but once it encodes the video it probably has to transcode from there to make it all fit on a single disc. it's very common for this to take many hours.
is this a new development? like did it used to more wuickly and it suddenly slowed down are are you just ffrustrated with how slow it is?
i'm not familiar with MyDVD so I can't tell you what's average, but anytime you're creating a DVD it's going to take a long time.