use Benchmark qw( cmpthese ) ;

my $wait = -34;

    cmpthese( -2, {
    a=>sub{
                $wait = $wait  < 0 ? 0 : $wait ;
                $wait = -34;
                },
    b=>sub{
                if ($wait < 0 ){ $wait = 0};
                $wait = -34;
                },

    c=>sub{
                $wait = 0 unless $wait > 0;
                $wait = -34;
                },

    d=>sub{
                $wait = 0 unless abs($wait);
                $wait = -34;
                },