In response to your clarification...
You could use ctypes to execute the c function "strcasecmp". Ctypes is included in Python 2.5. It provides the ability to call out to dll and shared libraries such as libc. Here is a quick example (Python on Linux; see link for Win32 help):
from ctypes import *
libc = CDLL("libc.so.6") // see link above for Win32 help
libc.strcasecmp("THIS", "this") // returns 0
libc.strcasecmp("THIS", "THAT") // returns 8
may also want to reference strcasecmp documentation
Not really sure this is any faster or slower (have not tested), but it's a way to use a C function to do case insensitive string comparisons.
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ActiveState Code - Recipe 194371: Case Insensitive Strings
is a recipe for creating a case insensitive string class. It might be a bit over kill for something quick, but could provide you with a common way of handling case insensitive strings if you plan on using them often.