xor: how come so slow?

[bearophileHUGS at lycos.com]

Few suggestions for your code:
- Use xrange instead of range.
- Loop over lists where you can instead of their indexes.
- array.array("B", somestring) may help you because it gives a byte
"view" of a string.
- Using psyco helps a lot for such kind of code.
- I think numpy arrays can contain text/chars too, so it may offer you
ways to speed up your code a lot.
- Generally Python is fit to download pages from the net or to act as
glue between different subsystems, or to do bulk string processing,
etc, but for grunt low-level works like this it's often too much slow,
and you can use other lower-level languages.
- You can use a lib already written, or use an extension, for example
you can try ShedSkin, or Pyd.

Bye,
bearophile