Benchmark built in Mongoid hooks against just calling functions normally.

benchmarking

irb> def benchmark
irb>   s = Time.zone.now
irb>   50000.times { yield }
irb>   e = Time.zone.now
irb>   e - s
irb> end
=> :benchmark
irb> benchmark do
irb>   u = RollingUser.new
irb>   u.save
irb> end
=> 32.557828
irb> benchmark do
irb>   u = HookUser.new
irb>   u.save
irb> end
=> 49.877796

hook_user.rb

class HookUser
  include Mongoid::Document

  field :name, type: String, default: ''

  before_save do
    self.name = srand.to_s
  end
end

rolling_user.rb

class RollingUser
  include Mongoid::Document

  field :name, type: String, default: ''

  def save
    self.name = srand.to_s
    super
  end
end