From the description, it sounds like you're taking a big array and trying to split it into a number of smaller arrays. I'd have expected the most efficient approach to be to do everything in a single pass, rather than looping over the array several times.

That is to say, instead of

my @As = grep { /A/ } @bigarray;
my @Bs = grep { /B/ } @bigarray;
my @Cs = grep { /C/ } @bigarray;

[download]

I would write

my (@As, @Bs, @Cs);
for my $item (@bigarray) {
    if    ($item =~ /A/) { push @As, $item }
    elsif ($item =~ /B/) { push @Bs, $item }
    elsif ($item =~ /C/) { push @Cs, $item }
}

[download]

In reply to Re: Fastest way to grep multiple time on some array by Porculus
in thread Fastest way to grep multiple time on some array by Anonymous Monk

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