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On Mon, 18 Jun 2012 15:28:24 +0100
Mark Shannon <mark@hotpy.org> wrote:
>
> But do they? The results of benchmarking would seem to suggest (at least
> on my test machine) that overly-sparse dicts are slower.
> Possibly due to increased cache misses.

Or, at least, they are not faster. See the synthetic experiments in
http://bugs.python.org/issue10408

That said, Raymond might have witnessed different results at the time.
Hardware evolves quickly and the parameters change (memory latency
today is at least 50+ CPU cycles, which is quite a lot of wasted work on
a pipelined superscalar CPU).

Regards

Antoine.