#!/usr/bin/perl
use strict;
use warnings;

my @values = qw(test test1 test2 test3);

use Benchmark qw( cmpthese );

cmpthese -2, {
    for_loop  => sub { my @matches; for (@values) { push @matches, $_ if $_ =~ qr{test} }; },
    grep_loop => sub { my @matches = grep { $_ =~ qr{test} } @values;                      },
};
__END__
             Rate grep_loop  for_loop
grep_loop 66674/s        --      -10%
for_loop  74136/s       11%        --

This is perl, v5.8.8 built for i486-linux-gnu-thread-multi