Use substr when possible, it can be many times faster then a simple regex:
my $a = "abcdefghijklmnopqrstuvwxyz";
use Benchmark;
timethese(1000000, {
's1' => sub { s1($a, 5) },
's2' => sub { s2($a, 5) },
});
sub s1 {
my $a = $_[0];
$a =~ s/^.{$_[1]}//;
return $a;
}
sub s2 {
substr($_[0], $_[1]);
}
Results:
s1: 8 wallclock secs ( 7.95 usr + 0.09 sys = 8.04 CPU)
s2: 2 wallclock secs ( 2.54 usr + 0.01 sys = 2.55 CPU)
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