Why is String.IsNullOrEmpty faster than String.Length?

Question

ILSpy shows that String.IsNullOrEmpty is implemented in terms of String.Length. But then why is String.IsNullOrEmpty(s) faster than

Answer 1

You test is wrong somethere. IsNullOrEmpty can't be faster by definition, since it makes additional null comparison operation, and then tests the Length.

So the answer can be: it's faster because of your test. However even your code shows that IsNullOrEmpty is consistently slower on my machine in both x86 and x64 modes.