title: Cheapest way to copy an IEnumerable<T>?
body: <p>I've got an <code>IEnumerable&lt;T&gt;</code>, and I need a copy of it. Anything that implements <code>IEnumerable&lt;T&gt;</code> will do just fine. What's the cheapest way to copy it? <code>.ToArray()</code> maybe?</p>