How can I time a code segment for testing performance with Pythons timeit?

You can use time.time() or time.clock() before and after the block you want to time.

import time

t0 = time.time()
code_block
t1 = time.time()

total = t1-t0

This method is not as exact as timeit (it does not average several runs) but it is straightforward.

time.time() (in Windows and Linux) and time.clock() (in Linux) are not precise enough for fast functions (you get total = 0). In this case or if you want to average the time elapsed by several runs, you have to manually call the function multiple times (As I think you already do in you example code and timeit does automatically when you set its number argument)

import time

def myfast():
   code

n = 10000
t0 = time.time()
for i in range(n): myfast()
t1 = time.time()

total_n = t1-t0

In Windows, as Corey stated in the comment, time.clock() has much higher precision (microsecond instead of second) and is preferred over time.time().