IMO, that excuse doesn't hold water on 64 bit machines. On 64 bit machines, not using tagged pointers (using the CPU for fast arithmetic on word sized integers)

IMO, that excuse doesn't hold water on 64 bit machines. On 64 bit machines, not using tagged pointers (using the CPU for fast arithmetic on word sized integers) and instead using the slow branchy sign-magnitude representation that cPython uses for integers is unconscionable, in terms of both performance and memory usage.