If your video is really long, I would try to break it down into 2 or 3 segments. Produce each segment into a mpeg2 file, then combine the 2 or 3 final mpeg2 files into a new timeline and produce your final video. To do this, open your project.
Then remove say the final 1/2 of it, then go to "save as" and save as a new file name, thus your original is not altered.
Then do the same for the first half of it. Make sure to save as a new file name so you don't alter your original. Produce those 2 new videos into a mpeg2, then take those mpegs into a new timeling.

Its always a good idea to produce several small segments than 1 large one.

You can highlight large segments and cut or delete, rahter than doing 1 obect at a time.
Land of fieros, North Dakota USA