Timing of various functions on ATMEGA 328P chip (Arduino Uno, Arduino Nano, etc) [stub]

ASIDE:
This quite a useful discussion, despite the initial claims being questionable - it exposes the thinking and methods needed to optimise and understand the relationship between expectations and the results.

Compilers, optimisers and significant understanding is required before truly clean and efficient code can be delivered.
Thanks for starting the conversation OP !