($x,$y)=($y,$x);

##</code><code>##

use Benchmark 'cmpthese';
use strict;

my ($x,$y,$u)=(1,2);
sub swapL{
	($x,$y)=($y,$x);
}

sub swapTt{
	my $t=$x;
	$x=$y;
	$y=$t;
}

sub swapTu{
	$u=$x;
	$x=$y;
	$y=$u;
}

cmpthese (-10,{list =>\&swapL,
               mytmp=>\&swapTt,
               glbtmp=>\&swapTu});
__END__
Benchmark: running glbtmp, list, mytmp, each for at least 10 CPU seconds...
    glbtmp: 11 wallclocks (10.01 usr +  0.00 sys = 10.01 CPU) @ 1063530.80/s (n=10651261)
      list: 13 wallclocks (10.19 usr +  0.00 sys = 10.19 CPU) @  656331.40/s (n= 6686048)
     mytmp:  9 wallclocks (10.27 usr +  0.00 sys = 10.27 CPU) @  905807.23/s (n= 9299017)
            Rate   list  mytmp glbtmp
list    656331/s     --   -28%   -38%
mytmp   905807/s    38%     --   -15%
glbtmp 1063531/s    62%    17%     --