Take a look at the 128-bit variant of MurmurHash3. The algorithm’s page includes some performance numbers. Should be possible to port this to Python, pure or as a C extension. (Updated the author recommends using the 128-bit variant and throwing away the bits you don’t need).
If MurmurHash2 64-bit works for you, there is a Python implementation (C extension) in the pyfasthash package, which includes a few other non-cryptographic hash variants, though some of these only offer 32-bit output.
Update I did a quick Python wrapper for the Murmur3 hash function. Github project is here and you can find it on Python Package Index as well; it just needs a C++ compiler to build; no Boost required.
Usage example and timing comparison:
import murmur3
import timeit
# without seed
print murmur3.murmur3_x86_64('samplebias')
# with seed value
print murmur3.murmur3_x86_64('samplebias', 123)
# timing comparison with str __hash__
t = timeit.Timer("murmur3.murmur3_x86_64('hello')", "import murmur3")
print 'murmur3:', t.timeit()
t = timeit.Timer("str.__hash__('hello')")
print 'str.__hash__:', t.timeit()
Output:
15662901497824584782
7997834649920664675
murmur3: 0.264422178268
str.__hash__: 0.219163894653