Comment #42 on issue 2801 by [email protected]: Patch: Approximates cross-staff slurs in VerticalAxisGroup vertical-skylines.
http://code.google.com/p/lilypond/issues/detail?id=2801
Running tests now with a change - it looks like dead stubs were making it into the skyline, which was probably causing the garbage collection problems. I added a test to weed them out.
