The export may be reformatting the video to 29.97fps, which is why it takes so long.
But, if I understand your question, you’re exporting the file to use, unedited, in a motion menu. If this is the case, and you’re using DVD SP, you can avoid this step all together.
After exporting your MPG2 file and importing your assets into DVD SP, you can just drop your assest into your menu. You can adjust the starting point, the duration of the clip in the Menu Inspector.
Bruce Himmelblau
Chicago