Performance ordered dictionary vs normal dictionary

[Raymond Hettinger]

On Jul 28, 6:47 pm, Navkirat Singh <navkir... at gmail.com> wrote:
> I was wondering what would be better to do some medium
> to heavy book keeping in memory - Ordered Dictionary
> or a plain simple Dictionary object??

The current implementation of OrderedDict is based on regular
dictionaries, so it performance cannot be better than a regular
dictionary for the usual mapping operations.  Some accessor methods
like __getitem__(), __len__(), __contains__(), and get() are pass
throughs, so their performance is the same.  Most of the rest of the
methods are order aware and are slower by a constant factor.

So, if you don't need the ordering feature, then you're better-off
with a regular dictionary.

A potential future implementation for OrderedDict written in C would
have nearly identical performance as regular dicts for most operations
and slightly improved performance for iteration.

Raymond