sub fib_no_log {
my @fibonacci = (0, 1);
my ($n, $sum) = (1, 0);
while ($n < 1_000_000) {
$n = $fibonacci[$#fibonacci] + $fibonacci[ $#fibonacci  1 ];
push @fibonacci, $n;
$sum += $n if (($n % 2) == 0);
}
return $sum;
}
...
'fib_no_log' => sub { fib_no_log() },
and you will get this result:
Rate fib_log_buffer fib_log_buffer_is_chk f
+ib_no_log
fib_log_buffer 11712/s  13%
+ 68%
fib_log_buffer_is_chk 13525/s 15% 
+ 63%
fib_no_log 36540/s 212% 170%
+ 
Why? Because even the call to is_debug takes twice as long as the rest, the "meat" of your loop. Obviously you should have a perl_critic rule to warn from use of log4perl at all. Or avoid artificial benchmarks ;)
