math.sqrt(x) is significantly faster than x**0.5.
import math
N = 1000000
%%timeit
for i in range(N):
z=i**.5
10 loops, best of 3: 156 ms per loop
%%timeit
for i in range(N):
z=math.sqrt(i)
10 loops, best of 3: 91.1 ms per loop
Using Python 3.6.9 (notebook).