To run `pip install numpy psutil` and then `time python <script> <set size>`.

numpy_unique.py

import uuid
import sys

import numpy as np
import psutil

num_users = int(sys.argv[1])

users = np.unique(list(str(uuid.uuid4()) for _ in xrange(num_users)))
print len(users)
print '{} mb'.format(psutil.Process().memory_info().rss >> 20)

python_unique.py

import sys
import uuid

import psutil

num_users = int(sys.argv[1])

users = set(list(str(uuid.uuid4()) for _ in xrange(num_users)))
print len(users)
print '{} mb'.format(psutil.Process().memory_info().rss >> 20)