"I know that this is going to make all the Cnatics cringe but here it is:"

I'm not too sure what a 'Cnatic' is, but I guess I'm one of them.

"If you do not know the processor your C will not be optimum."

The whole point of 'C' is its platform independence. It is up to the implementation, not the programmer, to perform optimisations for a particular platform.

Performing the sort of 'micro optimisations' being discussed here to save a few cycles may make us feel very clever but are a waste of time unless absolutely necessary. They may actually reduce performance when code is changed elsewhere, or the compiler version is upgraded.

If 'micro optimisations' are necessary they are best done in assembler which will indeed require knowledge of the processor.

"No, there is no need to globally go back to writing assembler, but that does not mean that you do not need to know it."

Indeed, but you don't need to know it to write optimum 'C'.

"which is so called real C"

What is this 'real C' stuff anyway?