Measure the execution time with the “timeit” module

# The "timeit" module lets you measure the execution
# time of small bits of Python code

>>> import timeit
>>> timeit.timeit('"-".join(str(n) for n in range(100))',number=10000)
0.3412662749997253

>>> timeit.timeit('"-".join([str(n) for n in range(100)])',number=10000)
0.2996307989997149

>>> timeit.timeit('"-".join(map(str, range(100)))',number=10000)
0.24581470699922647