From http://unicode.org/faq/casemap_charprop.html :

Case folding is mostly used for caseless comparison of text, such as identifiers in a computer program, rather than actual text transformation.

I opened https://github.com/dotnet/corefx/issues/33047 to implement simple case folding.

We could use this for improving performance in:

• PowerShell identifer comparisons
• Select-String cmdlet
• some more (???)