For comparison, I get the same sort of speed on my system: %timeit p = pickle.dumps(a) 1 loops, best of 3: 1.14 s per loop But tostring and fromstring

For comparison, I get the same sort of speed on my system: %timeit p = pickle.dumps(a) 1 loops, best of 3: 1.14 s per loop But tostring and fromstring run in a fraction of the time. %timeit s = a.tostring() 1000 loops, best of 3: 1.13 ms per loop %timeit b = np.fromstring(s).reshape(800, 600, 3) 1000 loops, best of 3: 1.57 ms per loop np.all(a == b) True