The author speculates that Clang's inferior performance on C++ code may relate to Clang's focus on Objective-C, plus his use of a gcc newer than 4.2.<p>For what it's worth, I've seen a slight speed hit compared to gcc 4.2, in Clang-compiled binaries of an application I work on. That code is straight C, with lots of numerics, and lots of linked lists.<p>As for the author, I appreciate Clang's excellent diagnostics, and continue to use it as a second compiler.