Antoine and Raymond, thank you for the valuable feedback.

Attached is a revised version of the patch, which restricts changes to those directly related to moving elements in the keys and values arrays at the same time.  I apologize for having gotten a little carried away with optimizing.

I think I eliminated all of the significant style differences as well.  If you still see glaring style mismatches, please let me know.  It's possible that the differences aren't visible to my eyes. ;-)

http://codereview.appspot.com/3369042/diff/1/Objects/listobject.c

Please let me know what you think of the revised version.