# 3.15 `cPickle` -- A faster `pickle`

The `cPickle` module supports serialization and de-serialization of Python objects, providing an interface and functionality nearly identical to the `pickle` module. There are several differences, the most important being performance and subclassability.

First, `cPickle` can be up to 1000 times faster than `pickle` because the former is implemented in C. Second, in the `cPickle` module the callables `Pickler()` and `Unpickler()` are functions, not classes. This means that you cannot use them to derive custom pickling and unpickling subclasses. Most applications have no need for this functionality and should benefit from the greatly improved performance of the `cPickle` module.

The pickle data stream produced by `pickle` and `cPickle` are identical, so it is possible to use `pickle` and `cPickle` interchangeably with existing pickles.3.11

There are additional minor differences in API between `cPickle` and `pickle`, however for most applications, they are interchangeable. More documentation is provided in the `pickle` module documentation, which includes a list of the documented differences.

#### Footnotes

... pickles.3.11
  Since the pickle data format is actually a tiny stack-oriented programming language, and some freedom is taken in the encodings of certain objects, it is possible that the two modules produce different data streams for the same input objects. However it is guaranteed that they will always be able to read each other's data streams.