file_get_contents VS CURL, what has better performance?

I am using PHP to build a web crawler to crawl millions of URLs, what is better for me in terms of performance? file_get_contents or CURL ?

howto benchmark javascript code?

Is there a package that helps me benchmark JS code ? Im not referring the Firebug and such tools.

How to measure the perfomance of the jQuery code

I know some selectors are faster than others, and of course our own methods can be faster or slower.

PHP is slower than it should be

Originally, I posted this on ServerFault ... but perhaps it is more of a PHP lingual question.