[php] PHP header redirect 301 - what are the implications?

I have domain.com. If the user is logged in, it should load automatically domain.com/option-X where X is a predefined choice of the user.

So, I do this at the top of index.php:

header("Location: /option-X"); 

But, if the user is not logged in, I just choose automatically the first option like this:

header("HTTP/1.1 301 Moved Permanently"); 
header("Location: /option-a"); 

So, i have two questions regarding the implications of doing so:

1. Since the search engines crawlers won't be logged in, they will always get domain.com/option-a - does it affect them that it has a 301 header?
2. What could be the server cpu load of doing those redirects? I don't know how to make a test out of it. The current site (which has no redirects) has about 100k daily visits.

Search engines like 301 redirects better than a 404 or some other type of client side redirect, no worries there.

CPU usage will be minimal, if you want to save even more cycles you could try and handle the redirect in apache using htaccess, then php won't even have to get involved. If you want to load test a server, you can use ab which comes with apache, or httperf if you are looking for a more robust testing tool.

This is better:

<?php
//* Permanently redirect page
header("Location: new_page.php",TRUE,301);
?>

Just one call including code 301. Also notice the relative path to the file in the same directory (not "/dir/dir/new_page.php", etc.), which all modern browsers seem to support.

I think this is valid since PHP 5.1.2, possibly earlier.

Just a tip: using http_response_code is much easier to remember than writing the full header:

http_response_code(301);
header('Location: /option-a'); 
exit;

Make sure you die() after your redirection, and make sure you do your redirect AS SOON AS POSSIBLE while your script executes. It makes sure that no more database queries (if some) are not wasted for nothing. That's the one tip I can give you

For search engines, 301 is the best response code