It's not just performance -- the patch code is grotesque.  Lots of code 
would need to be changed just before the release candidate (usually a 
bad idea).  And the underlying problem doesn't seem to be one that has 
*ever* affected a real user since 2.2.  I have a hard time caring much 
about this problem.  

The minor performance hit only bugs me because it affects the inner-
loops of just about every piece of real python code -- everyone will 
pay a cost for this change.

Since the "problem" has existed so long with no ill effect, am 
unmarking the "release blocker" priority.  Would rather have a 
thoughtful discussion on alternatives along with a careful, thorough, 
efficient patch for a bug release version.