There's a retrospective here which addresses quite a lot of it: http://qinsb.blogspot.com/2011/03/unladen-swallow-retrospective.html http://qinsb.blogspot.com/2

There's a retrospective here which addresses quite a lot of it: http://qinsb.blogspot.com/2011/03/unladen-swallow-retrospective.html http://qinsb.blogspot.com/2011/03/unladen-swallow-retrospect... Partly it sounds like performance-critical code at Google tends to get written in a lower level language instead, so Python performance isn't as critical, even though they use it quite a bit. Agree that it'd be great if they helped out the PyPy team though, since it's showing such great promise and has some pretty impressive numbers already.