It looks you have built both versions. Have you tested them? I would recommend nesting all of your replaces instead of doing them one at a time over and over. You can convert the entire function to a single statement. This will lend itself to becoming an iTVF pretty decently. It will take some effort to nest all those replaces but it will end up being faster. The CLR version may be faster. You will have to test that yourself in your system against your data. 😀