This is what Benchmark is for. So if you want to time how long it took for that particular itteration of the loop through then you would do something like this.

use POSIX;
use Benchmark;

for (my $count = 0; $count <= 11; $count++) {
    my $bench_1 = Benchmark->new();
    ...
    # do some intense stuff here
    my $bench_2 = Benchmark->new();
    my $time_diff = timediff($bench_2, $bench_1);
    print "This interaction took: " . timestr($time_diff)
        . " on " 
        . strftime("%a %b %e %H:%M:%S %Y", localtime);
}
[download]

Update: Woops, flipped $bench_1 and $bench_2 to give the correct timing.