PHP Curl Slowness
CURL has some problems with DNS look-ups. Try using IP address instead of domain name.
Curl has the ability to tell exactly how long each piece took and where the slowness is (name lookup, connect, transfer time). Use curl_getinfo (http://www.php.net/manual/en/function.curl-getinfo.php) after you run curl_exec.
If curl is slow, it is generally not the PHP code, it's almost always network related.