As Ian Kelly said on Python-List:

<quote>
Micro-benchmarks like the ones [jmf] have been reporting are *useful*
when it comes to determining what operations can be better optimized,
but they are not *important* in and of themselves.  What is important
is that actual, real-world programs are not significantly slowed by
these kinds of optimizations.  Until [it] can demonstrated that real
programs are adversely affected by PEP 393, there is not in my opinion
any regression that is worth worrying over.
</quote>

I think this issue should be closed.