[Python-Dev] performance of {} versus dict()

[Stefan Behnel]

Donald Stufft, 15.11.2012 00:00:
> $ pypy -m timeit 'dict()'
> 1000000000 loops, best of 3: 0.000811 usec per loop
> 
> $ pypy -m timeit '{}'    
> 1000000000 loops, best of 3: 0.000809 usec per loop
> 
> $ pypy -m timeit 'def md(**kw): return kw; md()'
> 100000000 loops, best of 3: 0.0182 usec per loop
> 
> $ pypy -m timeit -s 'def md(**kw): return kw' 'md()'
> 1000000000 loops, best of 3: 0.00136 usec per loop

Yep, I really like the fact that optimisers can fold stupid benchmarks into
no-ops. I wonder why it fails so badly in the latter two cases, though. You
should bring that to the attention of the PyPy developers, they might want
to fix it.

Stefan