I confirm that the proposed code is equivalent to the existing code and is faster. The largest part (~70%) of the speed up is caused by replacing int() calls with direct attribute access to _ip. I'm wondering whether it is worth to get rid of int() calls in the rest of the code.

The overhead of using int():

* Looking up the "int" name in globals (failed).
* Looking up the "int" name in builtins.
* Calling the C function.
* Calling the Python function.