Not directly, but you can make a copy of the wall (hold C then click on the wall), then delete the first few nodes from the first wall and the last few nodes from the second wall.
A 10km wall is a big no-no I'm afraid. It's explained in the video, basically when you run the track it has to plot all of the wall all of the time so gobbles up processing power.
What you need is a whole load of short walls for a good frame rate.