I’m not sure that I understand your argument. If the code from which the resulting machine code is compiled is C, then it’s objectively “as fast as C” … because, at the end of the day, it actually is C. Being “as fast as C” means that your resulting program will perform as fast as a C compiler [worth its salt] can get you.
Your comparison to machine code (or human readable assembly code) is less useful in that such a statement means very little until one knows how said machine code is being produced (e.g., manually, from a IR, etc.).
Your comparison to machine code (or human readable assembly code) is less useful in that such a statement means very little until one knows how said machine code is being produced (e.g., manually, from a IR, etc.).