You could use Quicktime Pro. It lets you copy and paste segments of the movie. Open the movie in QTP and select the first half and cut it. Open a new file and paste what you cut. Save both. This just isn’t very precise. And I assume you need to split the movie so you can burn it on two CDs. So your segments will need to be precise.
Why the other programs are taking so long is that they are re-encoding the movie. As long as QTP can play it the cut-copy-paste method will be a lot faster. I would install Perian to make sure you have the best chance of QT being able to playback the movie.