Yes. The difference is the Python compiler is not optimizing out the float() conversion, so every time it creates the value 5.0 it is calling the float() conver

Yes. The difference is the Python compiler is not optimizing out the float() conversion, so every time it creates the value 5.0 it is calling the float() conversion on the literal "5". Different machine, so the timings are different from above, but here are some permutations: Float literal: $ python -m timeit '5.0' 100000000 loops, best of 3: 0.0152 usec per loop Integer literal coerced to a float: $ python -m timeit 'float(5)' 10000000 loops, best of 3: 0.146 usec per loop Float literal coerced to a float: $ python -m timeit 'float(5.0)' 10000000 loops, best of 3: 0.143 usec per loop Integer literal: $ python -m timeit '5' 100000000 loops, best of 3: 0.0152 usec per loop Float literal coerced to an integer: $ python -m timeit 'int(5.0)' 10000000 loops, best of 3: 0.155 usec per loop Integer literal coerced to an integer: $ python -m timeit 'int(5)' 10000000 loops, best of 3: 0.14 usec per loop