Are you sure it was Raymond? Well at least Larry Hastings (the person who was attempting Gilectomy) said something similar, but even then he actually was ok with that as long as multithreaded performance was better, but unfortunately even that was worse. The main problem is Python's grabage collection through reference counting. Changing the counter requires locks, which then require cache flush every time.
There was an attempt (I think in PyPy) to use Software Transactional Memory (STM) which would solve this problem, but apparently it is still difficult to do it and looks like it did not succeed.
There was an attempt (I think in PyPy) to use Software Transactional Memory (STM) which would solve this problem, but apparently it is still difficult to do it and looks like it did not succeed.