ctype performance benchmark

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I started with ctypes because it is the battery included with the
Python standard library. My code is very fluid and I'm looking for
easy opportunity to optimize it. One example is to find the longest
common prefix among two strings. Right now I am comparing it character
by character with pure Python. It seems like an ideal low hanging
fruit. With ctype I can rewriting a few lines of Python into a few
lines of C. All the tools are available and no third party library is
needed.

It turned out the performance fail to match pure Python. This function
is called million of times in an inner loop. The overhead overwhelm
any performance gain with C. Eventually I have found success grouping
the data into larger chunk for each API call. This is what I
originally planned to do anyway. I am only sharing my experience here
that doing fine grained ctype function call has its limitation.

I have looked into Pyrex before and I was quite confused by the fusion
of C and Python langauage. Perhaps it is time for me to give it a
second look. I just heard of Cython now and it also look interesting.
I think it is helpful for both project to articulate more clearly what
they are, how they achieve the performance gain and to give more
guidance on good use cases. On the other hand, perhaps it is just me
are confused because I don't know enough of the Python internal.

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