Benchmark: timing 1000000 iterations of defined, exists...
   defined: 21 wallclock secs (21.36 usr +  0.00 sys = 21.36 CPU)
    exists: 19 wallclock secs (18.45 usr +  0.00 sys = 18.45 CPU)

##</code><code>##

# %hash is a hash with values for one/two/tre/for

sub t_exists {
    1 if exists $hash{one};
    1 if exists $hash{two};
    1 if exists $hash{tre};
    1 if exists $hash{for};
    1 if exists $hash{xxx};
    1 if exists $hash{xxy};
    1 if exists $hash{xxz};
    1 if exists $hash{xyx};
}
...