For the little it's worth here, I'd take advantage of $. and $_. Minimize what you are doing millions of times; and then yes, run a handful in parallel. 

open(my $fh, '<', $file) or die("Can not open file $file to read!\n");
while(<$fh>) {
    chomp;
    my ($a,$b,$c,$d,$e,$f,$g,$h,$i,$j,$k) = split("\t", $_, 11);
    # do something real
}
print "\n# of lines: $.\n";
close($fh);

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In reply to Re: Optimise file line by line parsing, substitute SPLIT by hbm
in thread Optimise file line by line parsing, substitute SPLIT by go9kata

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