use Benchmark;

my $m=4;
my @a=(1,2,3,0);
my $x=0;
timethese(-10, {
        wheel => sub {$x = $a[$x]},
        equaland => sub {++$x==$m and $x=0},
        mod => sub {$x = ($x+1) % $m;},
        trinary => sub {$x = ++$x==$m ? 0 : $x }
} );

__END__

equaland:  23033.30/s 
trinary:   15301.14/s
wheel:     12993.17/s
mod:       12857.56/s