Performance comparison looking up indices of set bits in Perl bit-vectors using vec() versus unpack "b*" and regex

bitvec-thing.pl

use strict;
use warnings;
use Time::HiRes qw(time);

my ($SPARSEX, $SPARSEY) = (1100, 1);
my $DIMS = 50000;

sub set2 {
  my ($m) = @_;
  for my $y (0..int($DIMS / $SPARSEY)) {
    vec($m->[$y * $SPARSEY], $_ * $SPARSEX, 1) = 1 for 0..$DIMS / $SPARSEX;
  }
}

sub indget {
  my ($m, $y, $use_vec) = @_;
  my $row = $m->[$y];
  return [ grep vec($row, $_, 1), 0..$#$m ]
    if $use_vec;
  my $s = unpack("b*", $row);
  my @v;
  push @v, pos($s) - 1 while $s =~ /1/g;
  \@v;
}

$| = 1;
my $m = [];
my $t = time();
set2($m);
printf "set in %0.6f\n", time() - $t;
$t = time();
#use Data::Dumper; print Dumper
indget($m, 0, 1);
printf "with vec done in %0.6f\n", time() - $t;
$t = time();
#use Data::Dumper; print Dumper
indget($m, 0, 0);
printf "with m//g done in %0.6f\n", time() - $t;
__END__
set in 1.004957
with vec done in 0.005272
with m//g done in 0.000131