Comment #56 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
Yup - I even made a test patch where I deleted all regtests save the problematic ones to speed up the process and the diff came out squeaky clean. So the presence of the other regtests does something to memory use that triggers this problem.
