Benchmarking is a good way to understand how Perl works and how to distinguish good code from bad code. However the sole requirement of Perl Golf is to achieve the desired effect in the least number of characters. Efficiency doesn't come into it. If anything that sport would be sprinting.
This is not to say that I wouldn't like to see benchmark comparisons of code, just that it isn't Golf. Call it Perl 100m or something else. :-)