When I run following script:

def uncalled():
    x = b'x' * (2**32)
print('Hello')

Python 3.4 consumes huge memory in spite of uncalled() function isn't called.

$ /usr/bin/time  -l /usr/local/bin/python2 constant_folding.py
Hello
        0.02 real         0.01 user         0.00 sys
   4337664  maximum resident set size

$ /usr/bin/time  -l /usr/local/bin/python3 constant_folding.py
Hello
        2.76 real         1.36 user         1.39 sys
4300234752  maximum resident set size

Both of Python 2.7.6 and Python 3.4.0 is built with Homebrew.