use strict;
use warnings;
use Benchmark 'cmpthese';

my @a = map log, 1..1e6;

cmpthese( -2, {
    1 => sub {[ map $_ * 4, @a ]},
    2 => sub {[ map $_ / (1/4), @a ]},
});

__END__

    Rate    1    2
1 7.70/s   -- -27%
2 10.6/s  38%   --

##</code><code>##

>perl -MDevel::Peek -E "$x=2/1; Dump$x; $y=$x*2; Dump$x; Dump$y"
SV = NV(0xd75628) at 0xd75640
  REFCNT = 1
  FLAGS = (NOK,pNOK)
  NV = 2
SV = PVNV(0xe26078) at 0xd75640
  REFCNT = 1
  FLAGS = (IOK,NOK,pIOK,pNOK)
  IV = 2
  NV = 2
  PV = 0
SV = IV(0xd75a80) at 0xd75a90
  REFCNT = 1
  FLAGS = (IOK,pIOK)
  IV = 4