Comment #57 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
git checkout release/2.17.2 lily/parser.yywill also change the memory allocation/release patterns significantly. lilypond -ddebug-gc might cause some changes. Sorry, this is all poking around in the dark.
