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?

You can share your changes by going to the Source Code tab and clicking on the Upload Patch link.

I think we would probably want to explore the case insensitive version a bit more as pretty much every SSAS instance I've worked on has been using the case insensitive collation. 

How did you measure the performance change? Did you run it from SSAS and include the marshalling time?

Thank you for reply!

I upload current version of StringFilters.

>>How did you measure the performance change? Did you run it from SSAS and include the marshalling time?

I have a dimension with about 200 000 items. It has strings with length from 10 up to 250. I execute queries in Management Studio and see execution time in status bar in bottom right. On my test data execution time was about seconds and ten's of seconds. Management studio was on the same server (with SSAS instance). You can compare results by compyling ASSP with my patch and creating new instance of ASSP assembly (with another name) and try to run identical queries several time (using current and patched ASSP).