You're missing the point. In addition to any performance differences, the snippet has other subtle differences from grep, some of which are undesirable. Typing

$ grep '| rm -rf *' 'ouch'
[download]

would not have done anything unexpected at all.

If you want to demonstrate that a simple Perl program is better or faster than a long-standing utility, you need to put more thought into what that utility does. Otherwise the comparison is unfair or meaningless.