I've got a PHP page that will get its content by looking into making an HTTP request to a different site on a single server, using file_get_contents. Both sites run in Apache 2 which calls PHP using suPHP (that is FastCGI, right?)

How significant may be the overhead of the call? Does Apache perform a large amount of processing before delivering a request to PHP?

Another way to create the phone call could be for that first site to exec('php /the/other/script.php some parameters'). Would this be faster, or perhaps is the overhead of breeding a procedure bigger compared to dealing with Apache?

Apache's over mind will rely on what is set up for your site host, for instance https, htaccess inspections, spinning, etc.. Individuals things can compare. Now i dont think it might be much strain overhead smart comparatively but you will possess the time that it taks to create the response which with respect to the character from the exterior pages oyure calling might be signifigant in certain situations.

With nevertheless, i dont nessecarily see an issue with making the calls through apache. However i think that while you suggest subjecting the php directly could be better. I believe maybe reading through on SOA generally may help you will get some insight how better to implement.

Unfotunatly setting up PHP as cgi, you'll loose a lot of performace, because eachtime you need to produce a new process for this. So most practical way would be to install PHP as apache modul