We have this issue triaged for at CPython hackathon in Boston.  Here is a patch for the issue.  

We only tested on Mac OS X 10.8.3,  which has zoned allocator,  so the memory profile is exactly the same with our without this patch.  The running time seems to be slightly better with the patch.  The benchmark we used runs for about 5.6 seconds with the patch vs.  5.9 seconds without the patch.  We run the benchmark multiple times and the results seem to be consistent.

Here are the results of the benchmarking and memory profile testing:

		With Fix	     		Without Fix

Mem	 1535 nodes (6377296 bytes)		1535 nodes (6378144 bytes)
Time     5.68					5.9 sec



The memory profile was measured by the MacOS X 'heap' command.  The timings come from attached benchmark module.  The original benchmark module is taken from here http://bugs.python.org/file25558/benchmark.py  and was modified to test this issue.