import time
import math
import numpy as np

def timeit1():
    s = time.time()
    for i in range(750000):
        z=i**.5
    print ("Took %f seconds" % (time.time() - s))

def timeit2(arg=math.sqrt):
    s = time.time()
    for i in range(750000):
        z=arg(i)
    print ("Took %f seconds" % (time.time() - s))

def timeit3(arg=np.sqrt):
    s = time.time()
    for i in range(750000):
        z=arg(i)
    print ("Took %f seconds" % (time.time() - s))

def timeit4():
    s = time.time()
    for i in range(750000):
        z=math.pow(i,.5)
    print ("Took %f seconds" % (time.time() - s))

timeit1()
timeit2()
timeit3()
timeit4()
 

Took 0.152364 seconds
Took 0.061580 seconds
Took 1.016529 seconds
Took 0.215403 seconds