Select Code to Download

use strict;
use warnings;
...
    @substrings = unpack( '(a3)*', $main::string );
    return \@substrings;
}

Benchmark: timing 10000000 iterations of control, match, substr, unpac
+k...
   control:  5 wallclock secs ( 5.65 usr +  0.00 sys =  5.65 CPU) @ 17
+69911.50/s (n=10000000)
     match: 22 wallclock secs (21.12 usr +  0.00 sys = 21.12 CPU) @ 47
+3484.85/s (n=10000000)
    substr: 12 wallclock secs (11.88 usr +  0.00 sys = 11.88 CPU) @ 84
+1750.84/s (n=10000000)
    unpack:  8 wallclock secs ( 9.04 usr +  0.00 sys =  9.04 CPU) @ 11
+06194.69/s (n=10000000)