curl is an extension that needs to be installed, it’s got nothing to do with the PHP version. http://www.php.net/manual/en/curl.setup.php
Your latest PHP/MySQL website is finally online. And it’s awesome. But it’s not as fast as you want it to be, because of the many SQL queries running every time a page is generated. And above that, you have the feeling it will not scale well under heavy loads. And you are most likely right.