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() },

##</code><code>##

                        Rate fib_log_buffer fib_log_buffer_is_chk    fib_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%            --