Wondering why the original benchmark didn't work as it should, lhoward said:

    > (I think its some sort of quoting/scoping problem,
    > but I'm not sure exactly what).
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It's a scoping problem. The quoted code (Grep2) isn't accessing the same %url hash as the other two pieces of code, which you could tell if you had warnings on. You get a warning about a "Useless use of list slice in void context" for that code.

Why aren't the others in void context? Grep is accessing the lexical %url because it's lexical to the file scope, and the Grep subroutine is defined in this file. And Grep3 (the third one) is accessing the same lexical %url because the anonymous sub acts as a closure (I think).

So Grep2 is looking at a different (not defined) %url, and is thus not actually a very good test in terms of benchmarking. :)