It's a pity this module is so slow. Unicode::ICU::Collator, which is a wrapper around the ICU library, is much, much faster. Unfortunately it doesn't work with ActivePerl and MinGW in Windows, since the Visual C ICU DLLs don't seem to be compatible with MinGW; the module crashes at ucol_open().
First off, to my shame, I've forgotten to rate this module until now.
Do you have the UCA (Unicode collation algorithm) off pat? If that is the case, I have nothing to say.
The module is an implementation of the UCA, which gives you the DUCET (Default Unicode Collation Element Table). Most of the time, however, you aren't satisfied with the DUCET, especially if you are a Japanese, Chinese, or Korean, etc. In that case, the module is highly recommended.
In addition, it's only natural that the module is included in the core, and the fact of being in the core is why I forgot to rate the module, too.