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 ?

file_get_contents with https?

I'm working on setting up credit card processing and needed to use a workaround for CURL, and the following code worked fine when I was using the test server (which wasn't calling an SSL URL), but now when I am testing it on the working server with https, it doesn't work ("failed to open stream").