My favorite tool for this is Benchmark::Timer.

use Benchmark::Timer;

my $T = new Benchmark::Timer;

$T->start( 'Outer' );

for( 1 .. 1000 ) { 

    $T->start( 'Inner' ); 

    # Request a 50 millisec delay to simulate command
    select undef, undef, undef, 0.05; 

    $T->stop( 'Inner' ) 
}; 
$T->stop( 'Outer' );

$T->report;

1 trial of Outer (199.094s total)

1000 trials of Inner (62.500s total), 62.500ms/trial
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