I made some changes that satisfy me (thread http://asstoredprocedures.codeplex.com/discussions/404654), but it requires some extra work, that, perhaps, will never be done by me.
The extra work to be done:
1. Add case sensitive "Like", "IsLike" based on custom algorithm (now it uses RegEx). Method will be faster 2-5 times.
2. Test case insensitive Like custom algorithm - I can't give any guarante that it's stable.
3. Some refactoring and optimizations.
Can I share current results with community as a patch?