def foo():
    x = 0
    y = 0
    for i in xrange(1000000):
        for xi, yi in [(x-1,y-1),(x,y-1),(x+1,y-1),(x-1,y),(x+1,y),(x-1,y+1),(x,y+1),(x+1,y+1)]:
            z = xi + yi
def bar():
    x = 0
    y = 0
    for i in xrange(1000000):
        for dx, dy in [(-1,-1),(0,-1),(1,-1),(-1,0),(1,0),(-1,1),(0,1),(1,1)]:
            xi = x + dx
            yi = y + dy
            z = xi + yi

import time
start = time.time()
foo()
print "foo took %.3fs" % (time.time() - start)
start = time.time()
bar()
print "bar took %.3fs" % (time.time() - start)

# Prints:
# foo took 1.680s
# bar took 1.563s