Failed experiment.

Hypotheseses:

1. Hiding a slow path in allocate is preferable to putting it in new, because allocate is much more rarely overridden.
2. Patching allocate would be more performant than new, because it's 0 arity and you don't need to pay any overhead to forward arguments.

Doesn't work at all, because an overridden allocate is not called by new.

class Foo
  class << self
    def allocate
      raise "This never gets called"
    end
  end
  
  def initialize
    puts "init"
    super()
  end
end

Foo.new # => only calls init

I thought the the default implementation Class#new would work something like:

class Class
  def new(...) = allocate.send(:initialize, ...)
end

Which is close, except the implementation in C makes a direct call to allocate, without dynamic dispatch: https://github.com/ruby/ruby/blob/a8cb7292c6790d12a72000c1e19e62f05ea63f6a/object.c#L2370