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;
                },


##</code><code>##

       Rate    a    b    c    d
a 4216652/s   -- -16% -17% -36%
b 5010637/s  19%   --  -2% -24%
c 5094673/s  21%   2%   -- -23%
d 6616606/s  57%  32%  30%   --


##</code><code>##

      Rate    a    b    c    d
a 3542992/s   --  -5%  -6% -50%
b 3742730/s   6%   --  -1% -47%
c 3766874/s   6%   1%   -- -47%
d 7084993/s 100%  89%  88%   --