action hooks in theme functions.php

@edrubins When a cached page is loaded, most of WordPress is not loaded. The whole idea behind caching is to capture the output of a WordPress page and store it as plain HTML. Then, when a request for that page comes in, the plain HTML version is loaded so as to avoid all the overhead generated by loading WordPress. That makes the pages load faster.

So to answer your question, no, the the_post action hook does not get called when a cached page is loaded.