Way back in The Perl Journal #11, I wrote about Benchmark.pm and compared map and foreach. In short, they come out roughly the same if you are doing the same thing. You're not doing the same thing in each though: one builds up a list to assign, and the other makes a bunch of scalar assignments. I talk about proper benchmarks and checking everything in Wasting time thinking about wasted time.

I have freely available text version of the article with no pretty graphs. It also shows up in Computer Science & Perl Programming: Best of The Perl Journal.