my $t;

sub a {};
sub b {};

multi sub c (1) {};
multi sub c (2) {};

for ^7 {
  my $iterations = ^10 ** $_;
  say $iterations.max ~ " calls";

  $t = now;
  for ^$iterations { $_ %% 2 ?? a() !! b() };
  say "regular: {now - $t}";

  $t = now;
  for ^$iterations { c($_ %% 2 ?? 1 !! 2) };
  say "multi:   {now - $t}";
}

##</code><code>##

1 calls
regular: 0.00630924
multi:   0.0046663
10 calls
regular: 0.00344620
multi:   0.00392575
100 calls
regular: 0.0056468
multi:   0.0079017
1000 calls
regular: 0.0238749
multi:   0.02800533
10000 calls
regular: 0.0541161
multi:   0.287505
100000 calls
regular: 0.43776129
multi:   2.39229575
1000000 calls
regular: 4.45541020
multi:   24.2623499

##</code><code>##

 
my $t;

class A {};
class B {};

sub a (A $a) {};
sub b (B $a) {};

multi sub c (A $a) {};
multi sub c (B $a) {};

for ^7 {
  my $iterations = ^10 ** $_;
  say $iterations.max ~ " calls";

  $t = now;
  for ^$iterations { $_ %% 2 ?? a(A) !! b(B) };
  say "regular: {now - $t}";

  $t = now;
  for ^$iterations { c($_ %% 2 ?? A !! B) };
  say "multi:   {now - $t}";
}

##</code><code>##

1 calls
regular: 0.00321471
multi:   0.00306454
10 calls
regular: 0.0029107
multi:   0.0029139
100 calls
regular: 0.0032379
multi:   0.00331093
1000 calls
regular: 0.0091466
multi:   0.00742758
10000 calls
regular: 0.04885046
multi:   0.053550
100000 calls
regular: 0.5330036
multi:   0.5973669
1000000 calls
regular: 5.6755910
multi:   5.946978