[issue16465] dict creation performance regression

[Christian Heimes]

Christian Heimes added the comment:

The patch gives a measurable speedup (./python is a patched 3.3.0+). IMO we should apply it. It's small and I can see no harm, too.

$ for PY in python2.7 python3.2 python3.3 ./python; do cmd="$PY -R -m timeit -n 10000000 '{};{};{};{};{};{};{};{};{};{}'"; echo $cmd; eval $cmd; done
python2.7 -R -m timeit -n 10000000 '{};{};{};{};{};{};{};{};{};{}'
10000000 loops, best of 3: 0.162 usec per loop
python3.2 -R -m timeit -n 10000000 '{};{};{};{};{};{};{};{};{};{}'
10000000 loops, best of 3: 0.142 usec per loop
python3.3 -R -m timeit -n 10000000 '{};{};{};{};{};{};{};{};{};{}'
10000000 loops, best of 3: 0.669 usec per loop
./python -R -m timeit -n 10000000 '{};{};{};{};{};{};{};{};{};{}'
10000000 loops, best of 3: 0.381 usec per loop

$ for PY in python2.7 python3.2 python3.3 ./python; do cmd="$PY -R -m timeit -n 10000000 'int(\"1\", base=16)'"; echo $cmd; eval $cmd; done
python2.7 -R -m timeit -n 10000000 'int("1", base=16)'
10000000 loops, best of 3: 0.268 usec per loop
python3.2 -R -m timeit -n 10000000 'int("1", base=16)'
10000000 loops, best of 3: 0.302 usec per loop
python3.3 -R -m timeit -n 10000000 'int("1", base=16)'
10000000 loops, best of 3: 0.477 usec per loop
./python -R -m timeit -n 10000000 'int("1", base=16)'
10000000 loops, best of 3: 0.356 usec per loop

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nosy: +christian.heimes

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<http://bugs.python.org/issue16465>
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