[issue8685] set(range(100000)).difference(set()) is slow

[Antoine Pitrou]

Antoine Pitrou <pitrou at free.fr> added the comment:

The current patch gives much smaller benefits than the originally posted benchmarks, although they are still substantial:

$ ./python -m timeit -s "a = set(range(100000)); sd = a.difference; b = set(range(1000))" "sd(b)"
- before: 5.56 msec per loop
- after: 3.18 msec per loop

$ ./python -m timeit -s "a = set(range(1000000)); sd = a.difference; b = set(range(10))" "sd(b)"
- before: 67.9 msec per loop
- after: 41.8 msec per loop

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versions:  -Python 2.7

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Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue8685>
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