use Benchmark qw[ timethis ];
timethis( 10, sub { my $x = 'A' <=> 'B' } );

Argument "B" isn't numeric in numeric comparison (<=>) at (eval 12) line 1.
Argument "A" isn't numeric in numeric comparison (<=>) at (eval 12) line 1.
timethis 10:  0 wallclock secs ( 0.00 usr +  0.00 sys =  0.00 CPU)

            (warning: too few iterations for a reliable count)