Some microbenchmark results on 32-bit Linux:

$ ./python -m timeit -s "from random import getrandbits" -- "getrandbits(64)"
Before: 1000000 loops, best of 3: 1.41 usec per loop
After:  1000000 loops, best of 3: 1.34 usec per loop

$ ./python -m timeit -s "from random import getrandbits" -- "getrandbits(2048)"
Before: 100000 loops, best of 3: 5.84 usec per loop
After:  100000 loops, best of 3: 5.61 usec per loop

$ ./python -m timeit -s "from random import getrandbits" -- "getrandbits(65536)"
Before: 10000 loops, best of 3: 145 usec per loop
After:  10000 loops, best of 3: 137 usec per loop