If I add PHP includes to a page.
include('example.php') - It then has to load that file which would / could slow down load time correct? Right now I am making unnecessary redirects back to the a login page if the logins are wrong via javascript snippet that is inside my login.php page (which does all the login checking against the database). So in the address bar it shows "admin.php > login.php > admin.php" , but I don't ever want to show what file it is going to in order to test the logins, but I also do not want to include this inside admin.php because I'm afraid it might affect load time.
If you understand my question then suggestions would be helpful.
New HTTP requests (redirects) are always a bigger performance hit than includes, so there's no reason to use redirects (especially Javascript ones) if you're only concerned about the performance. So if I understand you I'd like to suggest that you just include the file.